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When in full bloom, Azaleas are irresistable, so visit your garden centre this spring to select your very own favourite, favourites!

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Rhododendron 'Flambeau'Rhododendron 'Flambeau'Azaleas and Rhododendrons must be one of the best-loved sights of spring, when their brilliant blooms are produced in such abundance, they almost totally smother the leaves. And, although these popular ornamentals bloom for only a relatively short season, by selecting various species, and newer cultivars with different blooming times, the blooming season can be extended greatly.  Azaleas and Rhododendrons are also grown for their wonderful form, and the evergreen varieties are perfect additions to any garden, providing structure, and an attractive backdrop for other garden plants, throughout the year. If you can provide their basic needs, and plant them carefully, they’ll give you decades of low-maintenance enjoyment.

Botanically, Azaleas and Rhododendrons both belong to the large Rhododendron genus of plants, which has about a thousand different species.  Gardeners generally call them “azaleas” or “rhododendrons,” but these are general terms which are used to describe many subgroups within the genus. To keep it simple, remember there are evergreen and deciduous Rhododendrons. Technically, Rhododendron is a term referring to the plants within the genus which have evergreen leaves, and usually ten stamens within the flower. Azaleas belong to the sub-genus Pentanthera, and are characterized by being deciduous, and having five stamens.

Rhododendron 'White Boquet'Rhododendron 'White Boquet'Rhododendron 'White Boquet'Rhododendron is a very widely distributed genus that is mainly native to the temperate regions of the northern hemisphere. The highest species diversity can be found in the moist, acid soils of the Himalayas, and the mountains of Indo-China, Korea, Japan, and Taiwan. There are also a significant number of tropical rhododendron species, from south-east Asia to northern Australia. Rhododendron is characterized mainly by shrubs and small trees, and large trees are rare. The smallest species vary in height from about 10cm to 1m; while the largest, Rhododendron giganteum, can reach up to 30m. Rhododendrons are extensively hybridized in cultivation, and there are over 28,000 cultivars in the International Rhododendron Registry, held by the Royal Horticultural Society.

The evergreen Rhododendron indicum and its many garden hybrids are the most popular and extensively grown species throughout South Africa, because they tolerate heat, and a much wider climatic range than most other types. In its native habitat of Japan, Rhododendron indicum flourishes in woodlands, and thrives near water, especially alongside riverbanks and dams. Its showy flower displays can appear either in late winter and spring, or autumn and spring, depending on the variety. By choosing early, mid-season, and late flowering cultivars, you can have evergreen azaleas in bloom for a number of months. Single or double blooms are available in all shades of pink, red, white, purple, lilac, and even orange. The shapes of the flowers range through tubular, starry, funnel, bowl, and bell-shaped, varying in size from extremely large doubles to tiny singles, so visit your local garden centre when they are in bloom, and select your very own favourite, favourites! These low growing hybrids also vary greatly in size, but generally remain under 1m. However, under optimal growing conditions, they can mature into much larger shrubs.

Rhododendron 'Claude Goyet'Rhododendron 'Claude Goyet'Rhododendron 'Claude Goyet'The deciduous, yet eye-catching Azalea mollis is less well-known in South Africa, and may be difficult to procure, so if you ever spot some in bloom, snap them up, they’re worth their weight in gold! They are well known for their profusion of large, lush clusters of 7 to 13 funnel-shaped flowers, which are long-lasting, and appear in late spring. These garden hybrids come in a delightful range of colours, from white to various shades of yellow, salmon, as well as red to rusty orange. They have a complex hybrid ancestry, usually between Rhododendron japonicum, and other species from Japan and China. Ghent Hybrids were bred in Belgium, and further hybridization was carried out at Knap Hill, and these are called “Knap Hill,” or “Exbury Hybrids.” Many of these hybrids have a gorgeous scent; unlike the true Azalea mollis, which has little or no fragrance. If you smell them, you will notice that the yellows and lighter colours seem to have the strongest scent. The deciduous Rhododendrons are also much showier than their evergreen cousins, growing slowly to form a neat rounded shrub, 120 to 180cm tall and 120cm wide; and putting on a brilliant show of foliage colours in autumn, especially in the cold regions of the country.

Azalea mollis 'Orange'Azalea mollis 'Orange'Azalea mollis 'Orange'In the Garden & Home:

Evergreen azaleas are very valuable ornamental plants with a naturally beautiful shape, so they are not only used for their flowers, but also to add structure to the garden all year round. They vary in size, from small, rather delicate shrubs that are happiest in pots, to the large, and hardy ‘indica’ varieties that seem able to survive all the climatic challenges that are thrown at them.

Deciduous azaleas are very hardy, and easy to grow. They do not enjoy too much shade, and in cool regions will thrive in full sun, making them very versatile in the garden. They will also grow in large containers, as long as the containers are placed where they are shaded during the heat of the day.

Both types are perfect for cottage and woodland gardens, where they can be planted along the edges of woodlands and pathways, where there is access to good light, and sufficient sunshine. Plant them in large groups next to sheltered ponds and dams, where the reflection of the blooms in the still water, will double their impact. These shrubs have fibrous, non-invasive roots, and are therefore frequently used around foundations, and can make an attractive hedge. They are also essential in Japanese gardens, and a favourite with bonsai growers.

Azalea mollis 'Yellow'Azalea mollis 'Yellow'Azalea mollis 'Yellow'Rhododendrons combine beautifully with other shrubs, perennials, bulbs, and annuals, which thrive in semi-shade, so try them with Fuchsias, Hydrangeas, Yesterday, Today and Tomorrow (Brunfelsia,) Camellias, Mirror Bushes (Coprosma,) Arum Lilies (Zantedeschia,) spring bulbs like Daffodils and Hyacinths, and annuals like Primroses.

In less than ideal climatic conditions, it is best to cultivate Rhododendrons in pots, which can be moved around the garden with the seasons, and if you care for them correctly, they will give you many years of pleasure.

There are thousands of azalea varieties, far too many to list here. The best way to select the right one for your garden is to consider the area you have available. If you have a small garden, look for a dwarf or smaller type. If you have lots of space to fill, some of the older, taller growing varieties are great choices. Remember that the height and spread given on the plant labels are just indicators of how big a plant could grow, and if the plants are growing under ideal climatic conditions, they can grow much larger,  so do your research before buying.

As shrubs go, azaleas are of the ‘little work, big reward’ variety, so they’re definitely worth considering for your garden landscape.

The many cultivars of Rhododendron simsii (often called Rhododendron indicum) are popular indoor pot plants, and if their specific needs are met, they can be grown indoors for a long time - read how to cultivate them below.

Rhododendron 'William Wylum'Rhododendron 'William Wylum'Rhododendron 'William Wylum'Cultivation:

Until recently azaleas have been considered mainly temperate to cool climate plants, and most new hybrids were developed in the northern hemisphere, where they tended to focus on late flowering hybrids, to avoid frost damage to the blooms. The small-flowered, evergreen, Kurume varieties, and the deciduous azaleas are hardier, and therefore more suitable for colder climates.  The deciduous Azalea mollis types can bear very harsh temperatures without any problems – up to -23°C. And, because they flower later in spring, the opening buds are not normally affected by late frosts. In very cold regions, shelter them from freezing winter winds, and protect the roots by placing a thick mulch of straw, dry leaves, or acid compost, around them in autumn.

In regions where it can get hot really quickly in spring and summer, the flowers are often damaged by the sun, but recently breeders in Australia and New Zealand have successfully encouraged early flowering hybrids, to avoid this. These exciting new varieties should flower for much longer, starting in late winter, but are unfortunately not suitable for regions subject to late frosts.

Although Rhododendrons can be grown successfully in many regions of South Africa, they absolutely thrive in the cool, mist-belt regions of the Hillcrest area of KwaZulu-Natal, and the misty highlands of Magoebaskloof, in Limpopo. In these regions they will even thrive in full sun, but in other regions, to survive the dry summer heat, it is vital that you choose the right position outdoors. These plants love a lightly shaded position, or full morning sun, but ensure that they are protected from the harsh midday sun, and remember, in too much shade, they will not bloom well. Healthy plants require a good air flow around their leaves, and do not enjoy growing in hot, enclosed courtyards, even if they are placed in a shady corner.

Rhododendron 'Rose Queen'Rhododendron 'Rose Queen'Rhododendron 'Rose Queen'Rhododendrons prefer acid soils which are rich in humus, so add generous quantities of acid compost to the planting hole. The plants will not thrive in soil containing chalk or lime, and if your soil is not ideal, it would be easier to grow them in containers.  Although the plants love growing close to water, they will not survive waterlogged soil, but because of their very shallow, fibrous root systems, they tend to dry out rapidly, and will require regular watering during dry periods throughout the year, but especially during hot summer days. When it is very hot and dry, hose down, or mist spray the leaves to improve humidity; and mulch the roots to keep them cool, using pine needles, grass clippings mixed with leaves, bark chips, or peat moss.

Feed once a month in the growing season with a fertiliser for acid-loving plants, and an occasional application of Epsom salts. This is especially important in early spring, when the buds begin to swell, and the plant starts producing new leaves.  Rhododendrons need very little pruning, but you can shape them up a bit right after they have finished blooming. Remove a few of the spindliest branches, and pinch back the tips of the other branches to encourage fullness - this should be sufficient to keep your azaleas in good shape. By midsummer the plants have already set next year’s flower buds, so avoid late-season pruning.

Rhododendron 'Dicky'Rhododendron 'Dicky'Rhododendron 'Dicky'How to Pot a Rhododendron:

If your climate or soil is not ideal for growing Rhododendrons, and you simply must have a few, plant them into containers. Their shallow root system makes them perfect for potting up, and they do not need very large containers either, especially the dwarf strains. Once you have selected your pot and covered the drainage holes with fine pebbles or crocks, half fill with a specialised potting soil for acid-loving plants. Products like, Floragard Rhodohum, is a ready to use speciality soil for planting limestone sensitive plants, and a wonderful product to use for potted specimens, as well as for those growing in garden beds.

Gently remove the plant from its container and place it on top of the soil, fill with the remaining soil, tapping it down gently. Make sure that the plant is not buried too deeply, or it may rot.  Water thoroughly and mulch with a suitable material. Clay aggregate pebbles work well to keep the roots cool and well aerated. Place the pot in a shaded position and keep the soil moist but not sodden. No further feeding will be required until the plant is well established, after which it can be fed with a liquid fertiliser for acid-loving plants.

Rhododendron 'Rubra'Rhododendron 'Rubra'Rhododendron 'Rubra'Growing Azaleas Indoors:

The many cultivars of Rhododendron simsii (often called Rhododendron indicum) are popular indoor pot plants which are ‘forced’ to bloom in warm, humid conditions, making them available out of season. These frost tender evergreens do not do well outdoors in cold regions, and will grow 45 to 60cm tall, with an equal spread.

If their specific needs are met they can be grown indoors for a long time. They love a cool, humid atmosphere indoors, with plenty of indirect light. The plants will deteriorate if they suffer long periods in hot, dry conditions indoors. Mist the foliage down daily, and water as needed, to encourage new root and shoot growth. Rain water is the best, as hard water can damage potted azaleas. Remove spent flowers regularly, and once the plant has finished blooming, if you can, place it outdoors for a couple of months, selecting a spot which is sheltered and cool, with bright shade. Feed regularly during the growing season with a liquid fertiliser for acid-loving plans, and bring your plant indoors again in autumn, to overwinter. Potted azaleas are not the easiest of plants to get to re-flower indoors, but it is possible with a little TLC, and hopefully yours will reward you with flushes of flowers for many years.  

Rhododendron 'Little Girl'Rhododendron 'Little Girl'Rhododendron 'Little Girl'Propagation:

If you want plants that are identical to the parent plant, you will have to grow them from semi-ripe cuttings taken in mid-summer. Make short cuttings, 6 to 7cm long, and remove flower buds and any excess foliage. "Wound" the base of cuttings by removing some bark on both sides with a sharp knife, before dipping the end of each cutting in a rooting hormone, and inserting the bottom inch of the cutting into container filled with potting medium (1/2 Peat, 1/4 Sand, 1/4 Perlite.) Enclose the containers in clear plastic bags, to increase humidity, and place in bright window out of direct sun, or preferably under fluorescent lights with "long day" conditions (16 to 24 hours of light each day.) Keep the soil moist but not wet, since excess moisture causes rotting.

Cuttings should root within 2 to 4 months, but often it is better to leave them undisturbed for another month or so, to ensure that a substantial root system will be present before repotting. After potting them into individual little pots, keep them evenly moist, but a little on the dry side, to encourage root growth. For their first winter, continue to grow them under lights indoors, or provide cold frame protection outdoors. In spring, feed with a very weak liquid fertiliser for acid-loving plants, and once all danger of frost is over, move the pots outdoors into a cool, shady spot to acclimatise. Once your plants are nice and strong, plant them out into the garden or larger pots. In cold regions they will need winter protection for their first year outdoors.

Problems, Pests & Diseases:

A healthy Rhododendron, growing in the proper environment, and with the proper care, should have few problems. Occasionally they can be bothered by insects and diseases, which are more prevalent if the plants are grown in enclosed, or walled-in spaces, and especially underneath roofs. Watch out for insects like aphids, lace bugs, mealybugs, spider mites, scale, thrips, and whitefly. These can be controlled with an organic insecticide. They can also be affected by diseases like petal blight, black spot, rust, and powdery mildew, which can be controlled with an organic fungicide.

Azalea gall attack is a very distinctive and curious-looking disease which forms galls, varying in size from that of a pea to a small plum. These can grow on the leaves or the flowers, and the leaf or flower involved is practically replaced by the fleshy, irregular gall. Galls start out pale green or very rarely reddish, later becoming white, due to a floury bloom, which is a superficial coating of fungal spores. Galls can affect certain rhododendrons and azaleas growing outdoors, and is often seen on indoor potted plants of Rhododendron simsii, the popular Indian azalea obtained from florists. This common disease is caused by the fungus Exobasidium japonicum, and although it disfigures the plant, it does not kill it. There are no fungicides available to amateur gardeners for the control of azalea gall; and because it spreads by airborne spores, remove and dispose of them immediately, before they become white and infectious. If the disease appears on indoor potted plants, avoiding an excessively moist atmosphere will help to control it. Because some cultivars are especially susceptible, if a plant is heavily and persistently affected, it is probably best to replace it. On outdoor specimens, it is thought that some insect pests may spread the spores of the fungus, and these should be controlled with an insecticide if possible.

Warning:

All parts of Rhododendron are poisonous to humans and pets if ingested. Symptoms include: Nausea, salivation, vomiting, weakness, dizziness, difficulty in breathing, and loss of balance. The pollen of many, if not all species of rhododendrons, is also probably toxic, being said to cause intoxication when eaten in large quantities.

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