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Condensed VersionGazania 'Giant Orange':

Gazanias are little rays of sunshine with their bright blooms, and stalwarts of the African summer garden. These herbaceous perennials are very adaptable and thrive in many habitats, tolerating salt laden air and strong winds.

There are a number of Gazania subspecies, cultivars, and hybrids available from garden centres, each with its own unique growth habit, with both trailing and clump forming varieties. Hybrids are available in a choice of colours ranging from bronze to red, orange, pink, yellow, cream and white. The large, satiny flowers can be of a single colour or in graded shades; and the bases of the petals often feature spots, dots or darker areas with distinctive contrasting stripes and mottling. In warm regions most varieties will produce flowers all summer, or year round, if planted in full sun.

The leaves of the Gazanias are alternately arranged and densely clustered along the stems. They are variable in appearance and shape; most commonly they are lance shaped but can also be spoon shaped. Some leaves are smooth edged and others are indented. Leaf colour varies from light to dark green although some varieties have grey leaves. The upper leaf surface is generally hairless but the underside is densely covered in fine white hairs.

Gazania rigens var. unifloraAlthough these fast growing, short-lived perennial plants grow best in the winter rainfall regions, flourishing in seaside gardens where they tolerate salt-laden air and strong winds; if they are planted in well-drained soil they will thrive in the summer rainfall regions.

They are often grown as summer annuals in severe frost regions of South Africa; but will tolerate moderate frost if they are planted in a warm, sheltered position in the garden; the roots are mulched in winter; the soil is well-drained; and the plants are kept fairly dry during very cold snaps.

It is essential that gazanias receive as much sun as possible because the blooms only open in the sunshine, closing at night. New varieties are being bred which are more tolerant of semi-shade and whose blooms open on overcast days.

Although they are drought hardy the plants respond well when watered judiciously during dry spells. Cut out the dead blooms frequently to encourage more flowers. Established plants can be planted out at any time of the year, and seeds are sown in spring, summer or autumn; in the winter rainfall regions the seeds are usually sown at the start of the rainy season.

(Gazania var rigens) 

This gazania is not known in the wild, but only from cultivated plants and is a parent of many of the gazanias sold in garden centres today. It is a tender perennial that features decumbent stems that spread along the ground; and narrow but variably-shaped, silvery-green leaves. The flowers of this species are orange with orange-brown disks. Hybrid cultivars come in a great variety of colours, including shades of yellow, orange, bronze or white, often with contrasting colours at the bases, forming a ring around the central disk.  

(Gazania krebsiana)

This gazania must be one of Namaqualand's most striking and well known perennial plants and is one of the parent plants for the many gazania hybrids that are offered in garden centres today. This gazania is extremely showy with its large brightly coloured flowers. The plants are semi-decumbent (a plant, which lies on the ground with tips turned upwards). Because of this growth habit they are referred to as tufted groundcovers; and when many individual plants growing together are in full bloom their flowers carpet the veldt in magnificent dark red to orange. This gazania has very distinctive foliage and mature leaves are usually compound and divided into small, narrow, regular lobes. They are rough to the touch, dark shiny green on the upper side and woolly white underneath.

Gazania krebsianaFull Version:

Description, History & Interesting Facts:

Gazanias are little rays of sunshine with their bright blooms and stalwarts of the African summer garden. They belong to one of the most economically important families, Asteraceae, which includes import food crops as well as garden favourites like Zinnias, Dahlias and Marigolds to name a few.

These herbaceous perennials have a very wide distribution range, mainly within the winter rainfall regions of South Africa; but can be found in virtually all the provinces, from Namaqualand in the west to the Eastern Cape and KwaZulu-Natal, extending into the Great Karoo, the Free State and some regions of Gauteng and the Lowveld.

They are very adaptable and thrive in many habitats, tolerating salt laden air and strong winds; and can be found growing along roadsides, in coastal dune vegetation, Fynbos, grasslands and bushveld, or exposed hills and stony ridges. They tolerate most soils, but grow exceptionally well in sandy soils.

There are a number of Gazania subspecies, cultivars, and hybrids available from garden centres, each with its own unique growth habit, with both trailing and clump forming varieties.

Hybrids are available in a choice of colours ranging from bronze to red, orange, pink, yellow, cream and white. The large, satiny flowers can be of a single colour or in graded shades; and the bases of the petals often feature spots, dots or darker areas with distinctive contrasting stripes and mottling. In warm regions most varieties will produce flowers all summer, or year round, if planted in full sun. The flowers are light sensitive and close in the evening and on cloudy days.

The Afrikaans common name botterblom (butter flower) owes its name to the fact that the ray florets are supposed to taste like butter when chewed. The English common name, terracotta gazania, refers to the terracotta colour of the flowers.  A distinctive characteristic of gazanias is that the flowering stalks contain a milky sap.

The leaves of Gazanias are alternately arranged, densely clustered along the stems, and variable in appearance and shape. Most commonly they are lance shaped but can also be spoon shaped. Some leaves are smooth edged and others are indented. Leaf colour varies from light to dark green although some varieties have grey leaves. The upper surface is generally hairless but the underside of the leaf is densely covered in fine white hairs.

Gazania 'New Moon' After flowering, each flower head will produce many small fruits, each one equipped with silky hairs which enable them to be dispersed far and wide by the wind; and seeds can remain viable for a number of years.

Gazanias are pollinated by a number of insects with bees, bee flies, beetles, butterflies and ants visiting its bright flowers; the mature seeds are often carried away by ants into their underground tunnels. Monkey beetles are more or less endemic to the winter rainfall region of South Africa and are essentially pollen feeders, and many species are gregarious, congregating in flowers to feed and mate. Interestingly, the markings at the base of the petals of G. krebsiana show a striking resemblance to monkey beetles.

Gazania rigens have now been naturalised in Australia, New Zealand, the coastal Mediterranean countries and parts of America.

Trailing Gazania, Strandgazania, Rankbotterblom, ububendle, Ubendle (Gazania rigens)

This plant is not known in the wild but only from cultivated plants; and is a parent of many of the gazanias sold in garden centres today. It is a tender perennial that features decumbent stems that spread along the ground; and narrow but variably-shaped, silvery-green leaves. The flowers of this species are orange with orange-brown disks. Hybrid cultivars come in a great variety of colours, including shades of yellow, orange, bronze or white, often with contrasting colours at the bases forming a ring around the central disk.  The blooms can appear all through summer and autumn, often to the first frost. The flowers close at night and on cloudy days. With its trailing stems, it is particularly useful in hanging baskets and containers, and makes a wonderful show in beds and borders.

(Gazania rigens var. leucolaena)

This gazania has a small distribution area along the Cape south coast from about Mossel Bay to Port Elizabeth, where it grows on sand dunes, often just above the high tide mark. It commonly grows together with Gazania rigens var. uniflora; and when in full bloom, the bright yellow flower heads are perfectly offset by the greyish white leaves, creating an attractive cheerful patch of colour.

Gazania rigens var uniflora Variegated(Gazania rigens var. uniflora)

This variety occurs from about Knysna in the Western Cape, all along the coast to the Eastern Cape, KwaZulu-Natal, Swaziland and also southern Mozambique. It is a low, spreading half-hardy perennial with large, bright yellow flower heads in summer. This tough, mat forming plant requires little maintenance and excellent for landscaping in harsh areas. It even withstands a fair amount of traffic and an excellent ground cover, is stunning massed in borders, and good for sandy coastal gardens.

Terracotta Gazania, Gousblom, Botterblom, Rooi Gazania (Gazania krebsiana)

This must be one of Namaqualand's most striking and well known perennial plants; and is a trademark of gardens and natural landscapes of this region. It is one of the parent plants for the many gazania hybrids that are offered in garden centres today and this wonderful water-wise plant thrives in gardens around the country, provided it is planted in a very sunny area and is not overwatered.

It has a very wide distribution range, and although it occurs mainly within the winter rainfall regions of South Africa, it also extends into the summer rainfall regions and can be found in virtually all the provinces of South Africa, from Namaqualand in the west to the Eastern Cape and KwaZulu-Natal in the east; extending northwards into the drier interior regions of the Great Karoo and the Free State; and into some parts of Gauteng and the Lowveld.

These adaptable plants flourish in various habitats but are most commonly found growing along roadsides, on flats or lower slopes, exposed hills, rocky outcrops and stony ridges. To a lesser extent they may be found in grassy situations, in montane vegetation and in coastal dune vegetation which is commonly referred to as Strandveld. Associated vegetation types include Succulent Karoo, Nama Karoo, Fynbos, Dry Valley Bushveld and Grasslands. Plants seem to tolerate a number of soil types but have a noticeable preference for clay and sandy soil.

This is an extremely showy plant with its large brightly coloured flowers and long flowering period. The plants are semi-decumbent (a plant, which lies on the ground with tips turned upwards). Because of this growth habit they are referred to as tufted groundcovers; and when many individual plants growing together are in full bloom their flowers carpet the veldt in magnificent dark red to orange. Some refer to the colour as terracotta, hence the common name, terracotta gazania. The flowers have dark brown markings on the lower quarter of the petals and these markings may contain black or white spots, adding to their allure. The terracotta gazania flowers from August till January reaching a peak in October and November.

Gazania rigens 'White'This gazania has very distinctive foliage and mature leaves are usually compound and divided into small, narrow, regular lobes. They are rough to the touch, dark shiny green on the upper side and woolly white underneath. Individual plants reach about 150mm high and spread about 200mm across.

The root system is fairly weak and consists of a series of quite shallow adventitious roots. In nature it has to adapt extremely quickly to its environment in order to survive; and in the very dry summer months the plants shrivel and all that is visible are a few very dry leaves. Under these conditions the plants may look dead but in fact the plant is just minimising its exposure to the hot sun and saving water loss through its leaves. As soon the winter rains arrive this shallow spreading root system reacts immediately by putting on growth; making it an excellent pioneer plant. These perennials are relatively short lived, lasting about three years, depending on growing conditions.

Uses:

Wild and domesticated herbivores are very fond of Gazania krebsiana and other members of the genus, making them valuable for pastures, especially in the dry areas of the winter rainfall region where denuded, trampled patches occur in the veld. Although not endangered, in Namaqualand they have become heavily reduced due to unwise subsistence farming. Beside the fact that Gazania krebsiana is a palatable plant, no medicinal uses are recorded.

In the Garden:

Gazanias are tough little plants that require very little maintenance, and make fantastic garden plants, provided they are not overwatered and are planted in full sun. The best floral displays are achieved by planting in massed displays of a single variety as a groundcover or border; or by using several species of gazania together. The trailing varieties are particularly good in pots, hanging baskets and window boxes.

Evergreen groundcovers such as Gazanias can slow down a wild fire, and are renowned for their vigorous growth, making them an excellent groundcover to prevent soil erosion on slopes. Click here to read my articles on Firescaping your Property

Gazanias are essential in water-wise and low maintenance gardens and tolerate high pollution in cities.

Plants that compliment Gazanias well include: Trailing Daisy (Dimorphotheca); Renoster arctotis (Arctotis); Kingfisher Daisy (Felicia); Pincushion Flower (Scabiosa); Lobelia and Carpet Geranium (Geranium incanum).

Gazania splendens 'Pink'Cultivation:

These fast growing, short-lived perennial plants grow best in the winter rainfall regions, flourishing in seaside gardens where they tolerate salt-laden air and strong winds. If they are planted in well-drained soil they will also thrive in the summer rainfall regions. They are often grown as summer annuals in severe frost regions of South Africa but will tolerate moderate frost if they are planted in a warm, sheltered position in the garden; the roots are mulched in winter; the soil is well-drained; and the plants are kept fairly dry during very cold snaps.  For best results in the garden, plant them in well-drained soil enriched with compost and water moderately during dry spells.

It is essential that gazanias receive as much sun as possible because the blooms only open in the sunshine, closing at night. New varieties are being bred which are more tolerant of semi-shade and whose blooms open on overcast days. Cut out the dead flowers frequently to encourage more flowers. Established plants can be planted out at any time of the year, but in the winter rainfall regions the seeds are usually sown at the start of the rainy season.

Propagation:

Perennials can be propagated by dividing them in early spring or autumn. Seeds can be sown in seed trays or well-prepared garden beds when the daytime temperatures are between 20 and 25°C. Cover the seeds with soil or vermiculite. They will take 7 to 14 days to germinate and will bloom about 12 to 16 weeks after sowing.

Pests & Diseases:

If grown correctly gazanias suffer from no serious insect or disease problems, but mealybugs are occasional visitors.

Overly moist soils which don’t drain well can lead to root and stem rot; also watch for leaf spot and powdery mildew.

Citrus psyllaCitrus trees can be so pretty, even in the smallest of gardens. They have gorgeous shiny green leaves, beautiful sweet-smelling flowers, and wonderful health-giving fruit packed with vitamin C and antioxidants. With the proper care, good cultural practices, and a favourable rootstock, a citrus tree is capable of producing fruit in excess of 50 years. One such example is the original Washington Navel orange brought first from Brazil to Washington D.C. - then to California - in 1873. One hundred years later it was still alive and producing fruit!

However, sometimes these beautiful trees can look very unsightly due to citrus psylla, which causes unsightly bumps on the leaves with a corresponding pit on the underside; this is especially prevalent on the fresh young leaves. These bumps are caused by citrus gall wasps which are also the transmitter of a major citrus disease known as greening. Greening is prevalent in the relatively cooler, high-lying areas (above 600m). Typical symptoms are yellowing of the leaves and malformed fruit. One side of the fruit does not develop normally and remains smaller, resulting in asymmetrical fruit. The smaller side remains greenish while the rest of the fruit turns orange. The disease is caused by a bacterium for which no chemical treatment is available. As greening is usually localised within one or two branches of the tree, it is advisable to completely cut out the infected branches. Saw them off as close to the trunk as possible. If the entire tree is affected, it would be better to remove the tree and replace.

Citrus trees have three growth flushes a year: one in August/September, followed by another in November/December and the last during February/March. Lemons are the exception, forming new leaves throughout the year. It is during these flushes that the trees are susceptible to psylla infestation. The female citrus gall wasp lays discernible orange-yellow eggs on the edges of the young leaves. When the eggs hatch, the young nymphs move to the underside of the leaves and establish themselves to feed, causing pock-like malformations on the leaves.

Control of the pest must be aimed at destroying the nymphs as soon as possible after they have hatched. Because all the eggs do not hatch at once, it is essential to use a spray with a fairly long residual action and to spray regularly - as subscribed on the bottle. Check your trees regularly for the eggs and begin spraying immediately, ensuring that all the leaves are thoroughly covered. Psylla also occurs on other related plants like our indigenous cabbage tree (Cussonia spicata). Unless the infestation is severe, the general health of the tree and its fruit will not be affected, but if the infestation is severe, spray with an organic insecticide that contains pyrethrins; but remember to spray responsibly and selectively because pyrethrins will also kill off many of psylla’s natural enemies. To control pysllid populations naturally, try to encourage good predatory wildlife in your garden like ladybirds, wasps, lacewings, spiders and birds; controlling ants can also be helpful.

Click here to read more on growing and selecting citrus trees for your region. 

Heteropyxis natalensis Condensed Version:

The lavender tree is a neat and well-shaped deciduous to semi-deciduous tree with a slender upright growth habit and a small rounded crown. The roots are non-invasive and the trees grows steadily to +- 5 to 10 metres tall and 4 to 5m wide; dependant on rainfall and climate.

The long, dark green glossy leaves have a subtle lavender scent when crushed, and are born on pendant branches. In spring the growth is flushed red and in autumn they provide good seasonal colour by turning yellow to russet-red, with the leaves persisting for most of winter before dropping. Anytime from December to March panicles of inconspicuous but sweetly fragrant cream to pale yellow flowers appear; followed by tiny dark-brown capsules, bearing numerous seeds. The single main stem is crooked; and the attractive bark is pale grey, often almost white, maturing to creamy-tan, with a contorted and flaky appearance.

This versatile and most attractive tree can be used almost anywhere but is particularly useful where space is limited, or in beds where sun-loving smaller plants can still grow happily underneath. Because it has non-invasive roots, and is a small to medium-sized tree, it is suitable for small gardens as well as large landscapes. 

This low maintenance tree thrives in high and low rainfall regions, but the spring and autumn colours develop best in dry regions. Mature trees are hardy but young trees must be protected from frost for the first year or two. It is extremely water-wise and will tolerate drought for up to six months once established. Although it prefers full sun, it will also grow well in light shade. This tree grows moderately fast (about 1m per year); for fastest growth, plant in good well-drained soil and water moderately during dry spells. Feed in spring with a balanced organic fertiliser, and mulch with compost.

Heteropyxis natalensisFull Version:

Description, History & Interesting Facts:

The lavender tree family is very small with only three species native to Southern Africa: Heteropyxis canescens; Heteropyxis dehniae and Heteropyxis natalensis.  Heteropyxis natalensis is the most well-known and occurs naturally on the coastal and inland regions of KwaZulu-Natal; and also in Limpopo, Mpumalanga, Swaziland and Zimbabwe; where it is commonly found growing at forest margins, on rocky outcrops and hillsides, and termite mounds.

It is a neat and well-shaped deciduous to semi-deciduous tree with a slender upright growth habit and a small rounded crown. The roots are non-invasive and the trees grows steadily to +- 5 to 10 metres tall and 4 to 5m wide; dependant on rainfall and climate. The long, dark green glossy leaves have a subtle lavender scent when crushed, and are born on pendant branches.

In spring the growth is flushed red and in autumn they provide good seasonal colour by turning yellow to russet-red, with the leaves persisting for most of winter before dropping. Anytime from December to March panicles of inconspicuous but sweetly fragrant cream to pale yellow flowers appear; followed by tiny dark-brown capsules, bearing numerous seeds, in March and May.

The single main stem is crooked; and the attractive bark is pale grey, often almost white, maturing to creamy-tan, with a contorted and flaky appearance. The wood is hard; very fine grained and a pale pinkish brown in colour.

Uses:

The dried leaves are used in herbal tea, potpourri, and to scent tobacco. Because the wood is exceptionally hard, it is ideal for use as fencing posts and to make charcoal.

Traditional healers prescribe inhaling the steam from a decoction of the roots to heal a bleeding nose; and the leaves and roots are used medicinally to treat worms in livestock.

Both the bark and leaves are browsed by kudu, grey-duiker and black rhino. Essential oil is extracted from the leaves of this tree and has considerable antimicrobial and antibacterial properties.

In the Garden:

This versatile and most attractive tree can be used almost anywhere but is particularly useful where space is limited, or in beds where sun-loving smaller plants can still grow happily underneath. Its rich green summer leaves, beautiful yellow-red autumn colours, and attractive bark offers year-round interest and this indigenous tree should be utilised more often where a striking alternative is required for landscape projects.

Because it has non-invasive roots, and is a small to medium-sized tree, it is suitable for small gardens as well as large landscapes. Its tidy growth habit makes it ideal for planting in groups and groves, for boundary plantings, as well as a feature plant on its own. 

It can also be planted in large containers and is a good choice for bonsai.

The flowers attract bees, wasps, butterflies and many birds; including the Whitebellied Sunbird, Fantailed Flycatcher and Blackheaded Oriole.

Cultivation:

This low maintenance tree thrives in high and low rainfall regions, but the spring and autumn colours develop best in dry regions. Mature trees are hardy but young trees must be protected from frost for the first year or two.

It is extremely water-wise and will tolerate drought for up to six months once established. Although it prefers full sun, it will also grow well in light shade.

This tree grows moderately fast (about 1m per year); for fastest growth, plant in good well-drained soil and water moderately during dry spells. Feed in spring with a balanced organic fertiliser, and mulch with compost.

Propagation:

Seeds germinate easily in well-drained moist soil and young plants are relatively quick growing. Sow in well-drained soil and cover the seed with a thin layer of compost. For speedy germination place the trays in a warm area.

This plant can also be propagated by cuttings, although the success rate using this method is very low. Fresh cuttings may be taken and rooted in pure sand; hormone will help promote rooting.

Condensed Version:Vepris lanceolata

The white ironwood is a truly beautiful evergreen tree or shrub. It varies greatly in height, depending on climate, and rainfall. Naturally in more exposed coastal and arid regions it remains stunted, growing +-5m tall; while in forested areas it may reach up to 20m. The narrowly elliptic leaves are densely covered with gland-dots and have a lemony scent when crushed. The white ironwood flowers from December to March, but the small greenish-yellow, star-shaped flowers are inconspicuous. Male and female flowers are borne on different trees. The small 5mm fruit ripens from May to July, turning black when ripe; and is also covered with gland-dots and has the same lemony scent as the leaves. 

The ironwood is one of the best choices for small gardens as it does not have a very aggressive root system; grows well in containers; and responds well to pruning, so can be kept to any size. 

The ironwood does extremely well in coastal gardens and is wind tolerant. It is easy to grow in full sun or semi-shade; and is semi-hardy to frost if planted in a sheltered position away from freezing winter winds, and is covered for the first couple of winters. Although it is water-wise and tolerates drought in its natural habitat, it will not flourish in very arid regions of the country. It adapts to most well-drained garden soils, but when planting, be sure to incorporate lots of compost to the planting hole and a generous amount of bone meal to give your plant a good start. Mulch well and water regularly for the first year or two for a quick growing, strong young tree.

Full Version:

Description, History & Interesting Facts:

The lovely white ironwood belongs to the Rutaceae family which includes rue, buchu and the citrus family; with the most noteworthy member of this family being the (Agathosma species) or Buchus, as they are better known. The Ironwood is a truly beautiful tree or shrub which grows wild all along the coastline from the Western Cape through to the Eastern Cape and into Kwazulu-Natal, occurring in dune, riverine and low-lying forests.  It can also be found in the woodland and escarpment forests of Mpumalanga, Limpopo, northern Gauteng, and the north-eastern section of the North-West Province. It also grows in tropical Africa as far as Kenya and on the islands of Mauritius and Réunion.

This evergreen plant varies greatly in height, depending on climate, and rainfall. Naturally in more exposed coastal and arid regions it remains stunted, growing +-5m tall; while in forested areas it may reach up to 20m. The narrowly elliptic leaves are densely covered with gland-dots and have a lemony scent when crushed; which is a characteristic of the Rutaceae family.

It flowers from December to March, but the small greenish-yellow, star-shaped flowers are inconspicuous. Male and female flowers are borne on different trees. The small 5mm fruit ripens from May to July, turning black when ripe; and is also covered with gland-dots and has the same lemony scent as the leaves.

The bark is smooth and grey to dark grey in colour and the wood is hard, heavy, strong, elastic and even-grained with a whitish to pale yellow colour.

Many birds like the Redwinged Starling and the Crested Barbet are attracted to the fruit; and caterpillars of the Swallowtail butterfly feed on the leaves. Reportedly porcupines eat the bark and are blamed for ring-barking the trees and ultimately causing their death.

Vepris lanceolata foliageUses:

Traditionally the leaves are burnt to dispel evil spirits; and the powdered roots are used to treat influenza and colic.

The wood is good for making wheel spokes, handles, roof beams, furniture, ornaments and turnery.   

In the Garden:

The ironwood is one of the best choices for small gardens with its lovely shiny evergreen leaves which shimmer in even the slightest breeze, and their wonderful lemony scent when crushed.

It does not have a very aggressive root system; grows well in containers; and responds well to pruning, so can be kept to any size; doing well as a bonsai.  If planted closely together and clipped regularly it can even be coaxed to form a lovely screen.

It can also be grown underneath the canopy of other trees in groves and wild or forest gardens. This water-wise plant provides light shade and is a valuable food source for birds in winter when food is scarce, and your plant will come alive at this time with feeding birds. It also attracts butterflies, bees and other insects to the garden.

Cultivation/Propagation

The ironwood does extremely well in coastal gardens and is wind tolerant. It is easy to grow in full sun or semi-shade; and is semi-hardy to frost if planted in a sheltered position away from freezing winter winds, and is covered for the first couple of winters. 

Although it is water-wise and tolerates drought in its natural habitat, it will not flourish in very arid regions of the country. It adapts to most well-drained garden soils, but when planting, be sure to incorporate lots of compost to the planting hole and a generous amount of bone meal to give your plant a good start. 

Mulch well and water regularly for the first year or two for a quick growing, strong young tree.

This tree grows moderately fast and does not have a very aggressive root system.

This tree grows easily from seed and the young plants transplant well.

Virgilia oroboidesCondensed Version:

Two popular species of the Keurboom; Virgilia divaricata and Virgillia oroboides are very similar and often confused with each other. Both species are small to medium sized trees with lovely feathery leaves and a rounded to broadly conical growth habit; branching close to the ground. They are very fast growing when young, reaching their full height in only a few years.  V. divaricata grows from 6 to 10m in height, rarely exceeding 10m; while V. oroboides can reach 10 to 15m tall. When the trees are young the bark is smooth and a silver-grey, but with maturity it becomes grey and rough.

Both trees produce dense terminal sprays of sweetly scented pea shaped flowers; and can flower sporadically out of season. V. divaricata has violet-pink flowers with dark purple tips and its main flowering season is in spring and early summer; while the blooms of V. oroboides are pinkish-white to white and generally appear in mid to late summer. The flowers are rich in nectar; attracting many insects and birds; and long flat brown seed pods containing follow the flowers. The leaflets of V. oroboides are greyish green in colour and both the leaves and the twigs are densely covered in conspicuous rust-coloured, velvety hairs, whereas those of V. divaricata are green and almost hairless.

The popular Keurboom will provide light shade and looks spectacular wherever it is planted, being suitable for both small and large gardens;  in smaller gardens plant Virgilia divaricata because its growth is more compact and it is amazingly beautiful when in full flower.

Although the Keurboom thrives in the winter rainfall regions it can be grown inland if it is watered well in the dry winter months. While mature trees can survive short spells of light frost, young trees must be protected for the first few years. The trees will grow equally well in full sun or semi shade and are adaptable to most light, well drained soils. Although it is able to withstand moderate drought once established, the trees grow best if watered well when young and during prolonged dry spells.

Virgillia divericataFull Version:

Description, History & Interesting Facts:

The Keurboom is a beautiful evergreen indigenous flowering tree which belongs to the pea and bean family (Fabaceae) and grows wild in a small, narrow strip along our south-eastern coastline. Two popular species; Virgilia divaricata and Virgillia oroboides are very similar and often confused with each other. Both are commonly found growing alongside streams and river banks; on forest margins, in thickets and on hillsides. Virgilia oroboides occurs below 1 200m along the coast from the Cape Peninsula to George.  V. divaricata is also found below 1 200m, but from the Klein Swartberg Mountains to George, and to Van Staden's Pass near Port Elizabeth in the Eastern Cape. It is abundant in the Knysna and Plettenberg Bay area, and especially along the Keurbooms River, which takes its name from this tree.

Both species are small to medium sized trees with lovely feathery leaves and a rounded to broadly conical growth habit; and branching close to the ground. They are very fast growing when young, reaching their full height in only a few years. V. divaricata grows from 6 to 10m in height, rarely exceeding 10m; while V. oroboides can reach 10 to 15m tall. Because they grow so quickly; they are relatively short lived, with an average lifespan of 15 to 20 years. When the trees are young the bark is smooth and a silver-grey, but with maturity it becomes grey and rough, with a trunk diameter of about to 60cm.

Both trees produce dense terminal sprays of sweetly scented pea shaped flowers; and can flower sporadically out of season. V. divaricata has pinkish-mauve to violet-pink flowers with dark purple tips and its main flowering season is in spring and early summer (August to November); while the blooms of V. oroboides are pale pink or pinkish-white to white and generally appear in mid to late summer (January to April); but trees growing near George have rose-violet or purple-violet flowers which generally appear in spring.

The flowers are rich in nectar; attracting many insects and birds, such as sunbirds, carpenter bees, honey bees and ants.  Doves and white-eyes love to nest in the branches, and in the forests the large handsome ghost moth (Leto venus) lays its eggs at the foot of the Keurboom so that the hatching caterpillars can bore into the wood. The Blue Butterfly or Lucerne Blue (Lampides boeticus) is also known to breed on Keurboom trees, as well as Lucerne.  Long flat brown seed pods containing up to 11 seeds follow the flowers; and these are often foraged by livestock and poultry.

Because Keurboom species are so similar it can lead to confusion between; and they are differentiated from each other by their leaves. The leaflets of V. oroboides are greyish green in colour and both the leaves and the twigs are densely covered in conspicuous rust-coloured, velvety hairs, whereas those of V. divaricata are green and almost hairless. Many horticulturalists still disagree as to whether Virgilia is one variable species or two separate species. At present they are regarded as two separate species; with V. oroboides being divided into two subspecies. The tree growing in the George district with its rose-violet-flowers and rust-coloured hairs on the leaves and twigs being classified as V. oroboides subsp. ferruginea; and the pale, pink-flowered plant with white hairs on the leaves and twigs that occurs from the Cape Peninsula to Swellendam being V. oroboides subsp. oroboides.

Uses:

In earlier times the wood was very much in demand and used to make furniture as well as yokes, spars, wagon-bed planks and rafters. The transparent gum that exudes from the bark was also used as a substitute for starch.

In the Garden:

Keurboom trees were cultivated in England as long ago as 1767 and are also grown in Australia and in the USA today, where they are also known as Tree-in-a-hurry or Cape lilac. A Keurboom is the perfect tree for a new, bare garden because it grows so fast it will take only two or three years before it will be creating shade, or a screen, and filtering the wind—which is an important consideration in Cape Town suburbs. It is also a perfect pioneer species for woodland development where it is planted with slower growing species like milkwoods, providing shade and wind protection for more tender plants. Because it sheds small branches and leaves regularly, it also provides valuable mulch for the soil.The popular Keurboom will provide light shade and looks spectacular wherever it is planted, being suitable for both small and large gardens;  in smaller gardens plant Virgilia divaricata because its growth is more compact and it is amazingly beautiful when in full flower. The Keurboom is a wonderful street tree and is often used in office parks and parking lots, or other built up areas where a fast growing shade tree is required. Because it branches low down it makes an ideal screening plant and windbreak.

Cultivation:

Although the Keurboom thrives in the winter rainfall regions it can be grown inland if it is watered well in the dry winter months. While mature trees can survive short spells of light frost, young trees must be protected for the first few years.

The trees will grow equally well in full sun or semi shade and are adaptable to most light, well drained soils. Although the Keurboom is able to withstand moderate drought once established, the trees grow best if watered well when young and during prolonged dry spells.

Propagation:

Virgilia is easily propagated from seed sown in spring or autumn; but because the seed coat is hard it requires some stimulation to initiate germination. Seeds can be soaked in hot water before sowing, or the seed coat can be cracked artificially. They also respond to stimulation by fire and can be treated with the Kirstenbosch Instant Smoke Plus Seed Primer. Sow in soil which drains well and at a depth of 0.5 to 1cm. Seed can also be sown directly into the ground and because they are highly fertile, can remain alive for up to 30 years. Seedlings can be transplanted after the first true leaves.

See under Bulbous Plants

Iris Bearded 'Bewilderbeast'Condensed Version:

Bearded irises have played a starring role in cultivation for so long that the origins of this enchanting perennial are shrouded in the mists of time. All of the ancestors of the bearded iris originate from central, southern and Eastern Europe; and the Near East; and most taxonomic botanists believe that modern bearded irises are the result of interbreeding among about fourteen wild iris species. Irises remain one of the most reliable of the flowering perennials, flourishing in gardens and botanical gardens around the world and gardeners can rest assured, that if grown correctly, bearded irises will put on a spectacular show in their gardens from early spring; with re-blooming varieties continuing through summer.

Irises come in amazing array of colours to suit every gardener’s taste; such as blue and purple, white and yellow, pink and orange, brown, and even black. Several of them also have a beautiful sweet scent, and many older folk will remember that the earliest iris hybrids were highly scented. A small selection of plants or tubers is usually held by garden centres at appropriate times during the season, but there are thousands of cultivars available from specialist suppliers. Bearded irises are stately, elegant plants, no matter whether they are short, medium or tall growing varieties, and will add spectacular colour to flower borders. They also provide excellent accent and contrast to garden beds with their fans of sculptured, sword-shaped, bluish green leaves, standing stiffly upright or curving gracefully at their tips.

Bearded irises are not at all difficult to grow and are great for beginner gardeners. They grow throughout South Africa, but are not well suited to the humid coastal regions of KwaZulu-Natal and the Lowveld. They thrive in regions with high summer rainfall like the Kwa-Zulu Natal mist belt, and grow well on the Highveld, with a cold spell below zero setting their clocks for flowering in spring.  In arid regions of the country they need year round watering, and in the winter rainfall regions they must be watered well in summer. Irises can be planted throughout the year and come into full bloom during spring and early summer - from August onwards. Generally they rest during the heat of midsummer and re-bloomers will have another flush of blooms in late summer. New improved hybrids are continually being bred for their re-blooming qualities; and in warmer climates some cultivars will bloom almost all season long.  

Irises are quite tolerant of less-than-perfect soils, but most importantly, they require good garden soil that drains well; water should never stand in the beds. Good air circulation is also essential around the plants and their roots. The plants flower best in full sun; but will grow in light shade +-5 to 6 hour’s direct sunlight. The flowers need protection from strong winds and some afternoon shade is beneficial in extremely hot climates.

Bearded Iris 'Night Magic' It is a common mistake to plant Irises too deeply, so plant your rhizomes at or just barely below the surface of the ground, ensuring that the tops of the rhizomes are visible and the roots are spread out facing downwards in the soil. However, in extremely hot climates or in very light soils, the rhizomes can be covered lightly with one or two centimetres of soil. They are generally planted +- 60cm apart, but can be spaced at 20cm if you need a more instant effect. Apply a thin layer of compost and a dusting of bone meal around the base of the plants each spring, this should suffice and give you beautiful blooms without any further feeding; but feeding in late summer and early spring with a balanced fertiliser high in potassium won’t do any harm. A common mistake gardeners make is to overwater their Irises; once established they are extremely water-wise and will only require watering when the top three inches of soil dries out. Less frequent deep watering is better than frequent shallow watering.

The rhizomes grow along the surface of the soil, sending leaf fans upwards and roots downwards from their growing end. During the heat of summer they become hardened, protecting them from pests and diseases; and they generally take a rest, with growth resuming again in late summer and autumn before the leaves die down completely and the plant enters a completely dormant state for winter. Remove limp or dead leaves and any other litter regularly; as well as the stems of spent blooms.  In autumn, trim away dead foliage and prune back healthy leaves to a height of 4 to 5 inches; and in cold regions apply a layer of mulch over the soil to help protect the roots from freezing temperatures.  In extremely cold regions the roots of the plants often heave out of the soil due to alternate freezing and thawing. If heaving occurs, don't try to force the plants back into the soil; rather cover both the rhizomes and the exposed roots with soil, straw, newspaper, or any organic material. Divide bearded irises every 4 to 5 years, preferably in late summer (April); or at least four to six weeks before the first frosts arrive. However, if not done at this time, and provided you take good care of them, they can also be divided in spring. Dig out the clumps and discard the old divisions in the centre of the clump; these sections have very few white feeding roots. Select only large new fans with leaves to replant.

Bearded Iris 'Color me Blue'Full Version:

Description, History & Interesting Facts:

The bearded iris belongs to the family Iridaceae, which has about 325 species and 50,000 registered varieties. It remains one of the most beautiful of the flowering perennials; and all of the ancestors of the bearded iris originate from central, southern and Eastern Europe; and the Near East. Their habitat is very diverse, with the majority of species growing in temperate Northern climates; some in deserts; some in swamps; a few in the cold far north; growing on grassy slopes, in meadowlands and along riverbanks. It is most likely that the plant was named after the Greek goddess Iris (iris being the Greek word for ‘rainbow'). In Greek mythology, and particularly in the Iliad (an epic poem attributed to Homer) Iris was a divine messenger who rode rainbows between heaven and earth, and according to legend, an iris grew wherever the footsteps of the goddess touched the earth; giving rise to one of the common names used for irises ‘flower of the rainbow.

Bearded irises have played a starring role in cultivation for so long that the origins of this perennial are shrouded in the mists of time; and it is believed that most of the crosses took place naturally due to the close proximity of the plants, and it's possible that early plants-men were breeding irises many centuries ago by selecting desirable irises from crosses made naturally by bees. Irises were not only cultivated for their great beauty, but also for their medicinal, culinary and cosmetic properties; and a depiction of an Iris can be found on the walls of an Egyptian temple that dates back as far as 1500 BC. Apparently the spread of irises can be attributed in part to the soldiers of the Ottoman Empire. The soldiers used to carry iris rhizomes with them for medicinal purposes, and because it was believed that the sword-like leaves of the iris would drive away evil spirits, whenever a comrade died an iris rhizome would be planted on his grave.

Most taxonomic botanists believe that modern bearded irises are the result of interbreeding among about fourteen wild iris species, and since the variations in size increased with these breeding’s, bearded irises have been split into six different groups, based on plant size and growth habit. Bearded irises are stately, elegant plants, no matter whether they are short, medium or tall growing varieties, and will add spectacular colour to flower borders. They also provide excellent accent and contrast to garden beds with their fans of sculptured, sword-shaped, bluish green leaves, standing stiffly upright or curving gracefully at their tips. In some varieties the leaves have a surprising and attractive purplish red tinge at the base.

Irises come in amazing array of colours to suit every gardener’s taste; such as blue and purple, white and yellow, pink and orange, brown, and even black. Several of them also have a beautiful sweet scent, and many older folk will remember that the earliest iris hybrids were highly scented. Because Iris was the Greek goddess for the messenger of love, her sacred flower has long been considered the symbol of communication and messages; so a gift of an Iris can be used to convey many emotions, based on their colours. For example a purple iris is symbolic of wisdom and compliments, blue symbolizes faith and hope, yellow symbolizes passion, and white symbolizes purity. Irises can be planted throughout the year and come into full bloom during spring and early summer, from August onwards. Generally they rest during the heat of midsummer and re-bloomers will have another flush of blooms in late summer and autumn. Modern hybrids are continually being bred for their re-blooming capabilities, resulting in varieties which will bloom almost all season.

Bearded Iris 'Art Deco'Uses:

At one time the roots or rhizomes of the iris became popular in the field of Western herbal medicine and were used for all sorts of ailments and complaints, but they are now used mainly as a fixative and a base for perfumery and, believe it or not, in the making of many brands of gin. The powdered root is called ‘orris root’ and is added to potpourris to fix the fragrance.

To make an essential oil the root has to be dried and aged first, which can take up to five years. It is then ground to powder, dissolved in water and distilled. In order to produce two kilograms of essential oil you require one ton of iris root.

Make your own perfume:

Iris root has a delicate fragrance and for many centuries was made into perfume by the Romans, Greeks and Italians. You can try your hand at making your own perfume at home, either with orris root powder bought from a chemist, or from rhizomes you have spare from your garden.

Add 60 grams freshly chopped iris root or 30 grams orris root powder to 100ml of vodka. Add essential oils or fresh herbs of your choice before sealing the bottle and letting it infuse for about two weeks; shake the bottle daily. If after two weeks the fragrance is not strong enough for your liking, the old herbs can be strained out and fresh ones added and allowed to infuse further. Once the perfume is to your liking, strain and decant into a pretty bottle.

Bearded Iris 'Armageddon'Culinary:

Iris root is referred to as ‘orris' root, particularly where herbal concoctions and fine cuisine are involved. It is one of the ingredients in ‘ras el hanout’, a complex blend of herbs and spices primarily associated with Moroccan cuisine, but also used across the Middle East and Northern Africa. Ras el hanout recipes include cardamom, nutmeg, anise, mace, cinnamon, ginger, various peppers, and turmeric, but 30 or more ingredients might be used. The spices are typically prepared by grinding together whole spices, dried roots and leaves.

In the Garden:

Irises are beloved ornamental plants in gardens and botanical gardens around the world. In the United Stated of America the Presby Memorial Iris Gardens in New Jersey, is a living iris museum with over 10,000 plants, while in Europe the most famous iris garden is arguably the Giardino dell'Iris in Florence, Italy;
which hosts a world famous iris breeders' competition annually. Irises, especially the multitude of bearded types, also feature regularly in shows such as the Chelsea Flower Show. Gardeners can rest assured, that if grown correctly, bearded irises will put on a spectacular show in their gardens from early spring; and re-blooming varieties, continuing through summer. When different varieties are planted together they make a most spectacular display; and the grey-green colour of the sword shaped leaves will add valuable accent and contrast to a flowering border. A small selection of plants or tubers is usually held by garden centres at appropriate times during the season, but there are thousands of cultivars available from specialist suppliers.

Bearded Iris 'Mesmerizer'Cultivation

Bearded irises are not at all difficult to grow and are great for beginner gardeners. They grow throughout South Africa, but are not well suited to the humid coastal regions of KwaZulu-Natal and the Lowveld. They thrive in regions with high summer rainfall like the Kwa-Zulu Natal mist belt, and grow well on the Highveld, with a cold spell below zero setting their clocks for flowering in spring.  In arid regions of the country they need year round watering, and in the winter rainfall regions must be watered well in summer. Irises can be planted throughout the year and come into full bloom during spring and early summer - from August onwards. Generally they rest during the heat of midsummer and re-bloomers will have another flush of blooms in late summer. New improved hybrids are continually being bred for their re-blooming qualities; and in warmer climates some cultivars will bloom almost all season long.  

Although they are easy to grow, irises do however have a few simple but important requirements. They will adapt to most garden soils, but most importantly, they require soil that drains well, and water should never stand in the beds. If you have heavy or clay soil, adding humus, compost, or other organic material will improve drainage; gypsum is an excellent soil conditioner that can improve most clay soils. A raised bed or planting on a slope are also ideal to plant irises in these conditions. Good air circulation is also essential around the plants and their roots. Prepare your beds well before planting by digging them over thoroughly and incorporating some compost and bone meal.  The ideal pH for irises is 6.8 (slightly acidic) but they are quite tolerant of less-than-perfect soils. The plants also flower best in full sun; but will grow in light shade +-5 to 6 hour’s direct sunlight. The flowers need protection from strong winds and some afternoon shade is beneficial in extremely hot climates.

It is a common mistake to plant Irises too deeply, so plant your rhizomes at or just barely below the surface of the ground, ensuring that the tops of the rhizomes are visible and the roots are spread out facing downwards in the soil. However, in extremely hot climates or in very light soils, the rhizomes can be covered lightly with one or two centimetres of soil. Tamp the soil down firmly to anchor the new rhizomes and water well until established.  Irises are generally planted +- 60cm apart, but can be spaced at 20cm if you need a more instant effect; but be patient because  perennials require time to grow. New growth may be noticeable within 2 to 3 weeks, beginning with a new central leaf in the fan. Depending on the time of planting, the maturity of the rhizome, and geographical location, there may or may not be blooms the first spring after planting.

Apply a thin layer of compost and a dusting of bone meal around the base of the plants each spring, leaving the rhizome exposed. This should suffice and give you beautiful blooms without any further feeding; but feeding in late summer and early spring with a balanced fertiliser high in potassium won’t do any harm. Place fertilizer around the rhizomes, not directly on them, and water thoroughly afterwards. Feeding too often with a fertiliser high in nitrogen will encourage prolific leaf growth at the expense of the blooms, as well as increasing the risk of root rot.

The rhizome, or swollen stem, is where the plant stores nutrients and moisture, enabling it to survive a certain amount of stress. These grow along the surface of the soil, sending leaf fans upwards and roots downwards from their growing end. During the heat of summer the rhizomes become hardened, protecting them from pests and diseases; and they generally take a rest, with growth resuming again in late summer and autumn before the leaves die down completely and the plant enters a completely dormant state for winter.

Because the feeding roots of Irises are very close to the surface of the soil, it is essential that you do not allow neighbouring plants or weeds to encroach on their growing space. They also require sunlight right down to the rhizomes at root level; so remove limp or dead leaves and any other litter regularly.  Remove the stems of spent blooms by cutting them off at ground level. Try to do this on a dry sunny day if you can so the wounds can heal quickly, thus minimising the danger of rot.

A common mistake gardeners make is to overwater their Irises; once established they are extremely water-wise and will only require watering when the top three inches of soil dries out. The watering frequency will depend to a great extent on your environment. After planting, water well and continue watering until the first good rain. If lack of rain persists, watering should be deep enough to penetrate the shallow root system. Less frequent deep watering is better than frequent shallow watering. Long periods of wet weather can soften and weaken the rhizome, allowing pests and diseases entry. The waxy coated leaves express the overall well-being of the plant, with healthy leaves having a bluish tinge and growing vigorously from the middle of each fan.

Break out all the bloom-stalks as soon as the flowering season is over to prevent contamination of your named varieties by chance bee crosses. If crossed seed ripens unnoticed and germinates, the new plants will not be true to the parent plant and are very often unattractive. So breaking out bloom-stalks right away is a good garden practice. This will also encourage a second bloom on re-blooming varieties. In autumn, trim away dead foliage and prune back healthy leaves to a height of 4 to 5 inches; and in cold regions apply a layer of mulch over the soil to help protect the roots from freezing temperatures.  In extremely cold regions the roots of the plants often heave out of the soil due to alternate freezing and thawing. If heaving occurs, don't try to force the plants back into the soil; rather cover both the rhizomes and the exposed roots with soil, straw, newspaper, or any organic material. This can be held down with pegged chicken wire if necessary.

Bearded Iris' Brides Maid'Propagation:

Divide bearded irises every 4 to 5 years, preferably in late summer (April); or at least four to six weeks before the first frosts arrive. However, if not done at this time, and provided you take good care of them, they can also be divided in spring. Dig out the clumps and discard the old divisions in the centre of the clump; these sections have very few white feeding roots. Select only large new fans with leaves to replant.

Problems, Pests & Diseases:

Irises’ susceptibility to various pests and diseases often depends on your geographic location and many diseases may or may not affect your irises. During the heat of summer the rhizomes become hardened, making it difficult for pests and diseases to gain entry. However, long periods of wet weather can soften and weaken the rhizome, providing slugs and snails a hearty meal; and increasing the chances of fungal diseases. Keeping your garden clean from debris goes a long way toward avoiding the conditions mentioned above. This, together with well-drained soil, and the right amounts of food and water, will go a long way to preventing pests, as well as diseases like Bacterial Leaf Blight, Fungal Leaf Spot, Bacterial Soft Rot and Fungal Crown Rot.

Caution:

Members of the Iridaceae family are toxic to dogs and cats, causing salivation, vomiting, drooling, lethargy and diarrhoea. It is mainly the rhizomes that are toxic, so it is unlikely that cats would dig them out, but if your dog does, and ingests them, it would be advisable to contact your local veterinarian. Thankfully, iris toxicity is generally considered mild to moderate, and short-lived.

White OilWhat is white oil?

Organic gardeners are always on the lookout for a good general-purpose insecticide, and if it is simple to make at home, it’s all the better. This white oil recipe is safe, very economical, and you can make up small batches as you require them, eliminating a build-up of pesticides in your cupboard which you often never use again, and then have to figure out how to dispose of safely. It is easy to use, efficiently kills soft bodied insects on contact, has only two ingredients, and can be made in minutes!

Commercially produced oils used for managing pests on plants are most often called “horticultural oils.” Horticultural oils are derived from petroleum sources, and are sometimes called “mineral oil,” “narrow range oil,” or “superior oil.” Other oils produced to control pests may also be made from plants, such as canola, neem, or cottonseed oil.

The advantages of using white oil for pest control is it is low in toxicity to humans, wildlife and pets, yet effective. Since oils are only active for a short time, they do not affect beneficial garden insects like: ladybugs, parasitic wasps, honey bees, etc. unless they are exposed to the direct spray. Oils also evaporate quickly and do not generally contaminate the soil or groundwater sources. They are also considered one of the few classes of pesticides to which insects and mites have not developed resistance. Repeating applications as soon as pests are noticed will effectively protect your plants.

Oils have different effects on insects and work in several ways: by coating the insects and suffocating them; acting as a poison by interacting with the fatty acids in the insect and/or interfering with their normal metabolism, or by disrupting how the insect feeds.

Oil will control various chewing and sucking insects and their eggs, on deciduous ornamental shrubs like roses and dormant fruit trees, as well as on evergreens like citrus. It is commonly used against mites like red spider mite and bryobia mite, aphids, whiteflies, thrips, citrus leaf miners, caterpillar eggs, leafhoppers and mealybugs; and is especially good on scale insects, including: red, purple, mussel, pernicious and soft brown scale. Oils can also be used against powdery mildew because its fungal strands grow on the surfaces of the leaves of susceptible plants.

Roses and deciduous fruit trees are only sprayed with white oil when dormant in winter, usually after they have been pruned, to control pests such as scale. The first winter application is usually carried out after pruning and a second application just before bud burst occurs. Proper timing is critical for success when using oils. When spraying dormant plants the oils should be applied just before the leaves or flowers show signs of breaking dormancy; that is, before "bud break." If sprayed too early, and before the insects are actively respiring, the oils will be less effective.

Citrus benefits from oil spraysCitrus should be sprayed when the fruits are about the size of a walnut and again about 2 months before harvesting. To control citrus leaf miner, spraying is done when a new flush of growth occurs, and the application is repeated every 5 to 14 days. Do not use oils on citrus trees in late autumn or winter, as this can sometimes cause increased susceptibility to winter injury, wait until after winter hardening has occurred before spraying.

With vegetables, to control mites, aphids and greenhouse whitefly, spraying is done when pests first appear, with repeated applications. The withholding period for edibles with commercially produced petroleum oils is 1 day before harvest. Plant based oils are safe for use on vegetables with no withholding period, so you can spray and eat on the same day, just wash thoroughly before eating as you normally would.

Oils can also be used on indoor plants to control scale insects, mealy bugs and spider mites, but remember some indoor plants such as maidenhair ferns are more sensitive to leaf damage, so it is recommended to test on a small area of foliage before using.

Winter or early spring spraying with oil plays a key role in controlling insects organically because during these months the natural enemies of most pests are less active, making it the ideal time for populations like scale to breed - so be on the lookout constantly and spray immediately. Also, during the cooler months there is less chance of plant damage.

Garden insects thrive in protected, shielded areas of the garden and also love hiding in secluded spots on plants, like under the leaves, and are therefore not always easily detected unless you really look for them. For this reason infestations are often high before gardeners even notice them, making them even more difficult to control, and why most insect infestations are only noticed when winter and early spring pruning is done, so use these cooler months to spray both your evergreen and deciduous plants to control various insects.

With the trend back to natural pest control methods, we’ve seen an increased interest in the use of vegetable-based oils for pest control in recent years. However, gardeners have been using oils for about 200 years, and they are considered one of the most useful pesticides available for managing pests on woody ornamentals and fruit trees, as well as on herbaceous flowers and vegetables.

CAUTION:

Although oils can be used throughout the year, to minimize the risk of plant injury when using white oil, spray in the cool of the morning or late afternoon. Avoid treating when temperatures are below 5°C or above 28°C, or when the relative humidity is above 90 percent.

Do not spray when plants are in flower, avoid treating drought-stressed plants, and do not spray with oils in autumn as this can cause winter damage to evergreens. If spraying in winter do so on a warm day, because in freezing temperatures the emulsion doesn’t hold together properly, and coverage is uneven. 

When spraying evergreens with oils, always ensure that the plant foliage is dry, and remember that because oils have a low residual activity, they must be sprayed directly onto the insect or mite, so ensure that you cover all plant surfaces and especially the undersides of leaves and stems where pests can hide. Avoid large spray droplet sizes by using a good garden pressure sprayer with an adjustable nozzle. Also, remember, it is never very effective to spray on a windy day, or in the heat of the day.

Please spray responsibly, even if you are using organic products. Never spray if you notice bees or other beneficial insects on or near the infected plants; and only spray the infested plants, not everything in sight! 

IMPORTANT NOTE: 

Although generally considered safe, oils can injure susceptible plant species. Symptoms of plant injury (phytotoxicity) may be acute or chronic, and can include leaf scorching and browning, defoliation and stunted growth. Phytotoxicity in plants usually occurs in those that are overly sensitive to chemicals, and soft-leaves plants like lettuce and hairy-leaved plants are generally sensitive to oils. Do not spray oils directly onto sensitive flower heads to prevent oil spotting. Stressed plants are also more prone to sensitivity than those that are well watered and healthy.

Injury can occur when tank mixed chemicals are applied in hot weather or when an adjuvant (sticker) or solvent is added to the tank mixture.

Do not combine oils with sulphur or sulphur-containing sprays such as lime sulphur as they can react with oils to form substances toxic to plants. Also, do not use horticultural oils within 30 days of a sulphur application because elemental sulphur can persist for long periods.

Some plants most commonly listed as being oil sensitive include: Azalea, Carnation, Fuchsia, Hibiscus, Impatiens, Photinia, Cryptomeria, Juniper, Japanese Holly, and actively growing Roses.

Before applying and spraying your plants with ANY TYPE of spray ALWAYS test the spray on a small area of the plant and wait for 24 hours to see if the plant is susceptible to spray damage.

With oil testing you can mix up a small batch and test all the plants you believe you could potentially use the oil on in the future. To remember which leaves or small branches you have sprayed, tie a small piece of red wool onto the branch, or anything that will indicate where the plants were sprayed and check-up 24 hours later. This is where a gardener’s journal comes in most handy. Take notes on the day of spraying: the date, the temperatures, and if applicable the humidity. Name the plants tested and the results – this will come in handy in the future because you are likely to forget.

If you are growing produce on a larger scale or in tunnels, commercially produced horticultural oils would be the most effective to use in the heat of summer, because by the additional processes of filtration, distillation and dewaxing, manufacturers produced the very light and highly purified petroleum-based horticultural oils available today, and these oils can be used in all seasons of the year and do not cause leaf burn if used according to directions. Because summer oils won’t control all stages of insect growth, regular monitoring, early detection of infestations, and spraying immediately is vital to control them.

White Oil Recipe:

This simple recipe is made up of: one part dishwashing detergent to two parts vegetable oil. Adjust the amounts to suit your needs.

While some recipes call for specific types of oil such as sunflower or canola oil, you can use any vegetable oil. Any dishwashing liquid like ‘Sunlight” will do, as long as it does not contain bleach.

Combine the dishwashing detergent and cooking oil in a jar or a bottle with a tightly fitting lid.  Secure, shake vigorously, and before you know it, the oil and dish soap will have combined to become a whitish, creamy mixture. Using a blender stick will work even quicker. To ensure that your oil is truly emulsified, leave it overnight, and if it separates, you will need to blitz it again.  If, after much shaking the mixture still does not emulsify, add more detergent until it does.

This concentrated white oil insecticide needs to be diluted, using 2 tablespoons per litre of water. Agitate the mixture well before and during spraying. You can store the concentrate for several months in a sealed container placed in a cool place. Be sure to label it identifying it as a pesticide - you don’t want someone accidentally using it as a dinner ingredient!

TOXICITY:

Environmental impact of any garden product can be broken down into the categories of toxicity, soil mobility, persistence and bioaccumulation potential.

If we compare the toxicity of the natural and synthetic petroleum oils, we see some differences. In general, they’re both classed as low in toxicity to animals, birds, bees and fish, but moderately toxic to earthworms and some other aquatic organisms such as molluscs.

If we have a closer look at human toxicity, we see that the petroleum oils do present a higher toxicity hazard in terms of chronic toxicity hazard in the areas of reproductive and developmental toxicity.