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Your regional gardening guide for May

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Strelitzia reginaeStrelitzia reginaeWhat to do in your garden in May

All Regions

May is a wonderful month in the garden and as the cold winter days approach, gardens in frosty regions revel in brilliant displays of berries and the autumn foliage of deciduous trees and shrubs. In the subtropical regions colour is provided by flaming poinsettias, strelitzia, bougainvillea and red-hot pokers; and in the winter rainfall regions the roses will be bursting into bloom. If your garden always looks dull at this time of the year, visit your local garden centre to select some late summer and autumn beauties to plant in your garden; these will be well established by next autumn and reward you with their bountiful displays.

In all regions fast maturing winter flowering annuals like Bokbaai vygies (Dorotheanthus), African or Namaqualand daisy (Dimorphotheca), pot marigolds (Calendula), nemesias, cornflowers and Virginian stocks can still be sown directly into garden beds. Remember that as the weather cools down germination of seeds will be slower, and in cold regions it may be prudent to buy established seedlings of slower growing varieties of winter flowers to plant out, so visit your local garden centre to select your winter favourites.

Nip out the first flowers on pansy and Iceland poppy plants to encourage bushy, strong growth; and feed your sweetpeas every two weeks with organic 3:1:5. Tie taller growing sweetpeas to a framework or trellis for support and remove any unnecessary tendrils and side shoots to ensure strong and healthy plants that will provide you with an abundance of flowers in spring. In the warmer subtropical regions of the country, sweetpeas grow best if sown in autumn, when the weather is significantly cooler. (Read our February article)

In warmer parts of the country seeds can still be sown; try alyssum, snapdragon (antirrhinum), English daisy (Bellis perennis), cineraria, columbine (Aquilegia), candytuft (Iberis), Canterbury bells (Campanula), satin flower (Godetia), delphinium, dianthus, foxglove, gazania, hollyhock, Iceland poppy, baby snapdragon (Linaria), lobelia, lupin, nemesia, pansy, viola, phlox, primulas, schizanthus, Virginian stocks and wallflower.

Tulips mixed. Picture courtesy www.hadeco.co.zaTulips mixed. Picture courtesy www.hadeco.co.zaTulips mixed. Picture courtesy www.hadeco.co.zaIn most regions of the country the soil temperatures have cooled down considerably and you should have finished planting out most of your winter and spring flowering bulbs last month; except for tulips which are planted later in May when the soil temperatures have dropped considerably. Daffodils and hyacinths can still be planted out in May; as well as ranunculus and anemones, which can be planted out every 2 weeks to extend their flowering time.

Liliums will be in stores towards the end of May; plant them out as soon as you can as they do not have a long shelf life, and in cold regions protect the growing tips from frost. The brown stems of established clumps should be cut off at ground level, and overcrowded plants can be lifted and divided this month, but remember that they resent disturbance and can be left undivided for up to 5 years. Nerines are flowering now, so feed and water them regularly. Stop feeding your amaryllis bulbs and reduce the amount of water you give them, in order to induce winter dormancy.

Feed and mulch your aloes and winter flowering red-hot pokers (Kniphofia) for a beautiful show in May. Kniphofia ‘Royal Strain’ flowers in winter, producing wonderful dark red to bright orange flowers with yellow bases. Kniphofia ‘Yellow Cheer’ can also be planted out now; it produces its yellow flowers in summer and autumn. Aloes planted in flower borders amongst other plants often receive too much shade and water, making them susceptible to rust, and if the days are still sunny and warm, powdery mildew can develop. Always position them in an open sunny position and avoid overwatering.

Continue treating your conifers against attack by the Italian aphid, and give them a light trim if necessary, ensuring that you don’t cut into the old wood.

Continue taking hardwood cuttings of evergreen and deciduous shrubs.

Burgundy Iceberg RoseBurgundy Iceberg RoseBurgundy Iceberg RoseIn the winter rainfall and subtropical regions roses put on a beautiful show in autumn and should still be fed. If black spot is a problem, spray with an organic copper based fungicide and remove all diseased leaves. In very cold regions you should have stopped fertilising; and your roses will be having their last flush of blooms and start going dormant now, so reduce watering. Deadhead your roses when they stop blooming; and in severely cold regions wrap the stems of your standard roses with a frost protection material or wrap them in straw, bound with twine; also mulch the roots of your plants with straw or any organic material. Tag any roses growing in the wrong position in the garden and which you wish to transplant in June or July.

Watch out for fungal diseases like rust and black spot on your roses, pelargoniums and geraniums. Spray the entire plant; as well as under the leaves with a fungicide.

In certain regions bare root roses, fruit trees, shrubs and trees are available from May to July and can be safely planted out during these months.

In the subtropical summer rainfall regions feed your lawn for the last time with a fertiliser which is high in nitrogen. Throughout the country, lawn growth will slow down, and as it does so you will be able to spot the weeds easier, making this an excellent time to weed by hand. In cold regions Kikuyu lawn will go dormant this month, but before putting away your lawn mower for winter give it a thorough clean and take it to a specialist lawnmower shop for a general overhaul and to have the blades sharpened. Ask them to sharpen your secateurs, long handled loppers and hedge clippers as well.

Hydrangea Renate Steinige. Picture courtesy Leonora Enking. Hydrangea Renate Steinige. Picture courtesy Leonora Enking. Hydrangea Renate Steinige. Picture courtesy Leonora Enking. To intensify the blue of your hydrangeas next season sprinkle the soil around them now with flowers of sulphur, using about 50 to 75g for each established bush. (Flowers of sulphur can be purchased from a chemist). Mulch them with acid compost, pine needles, bark chips, old tea bags or oak tree leaves. To increase the intensity of pink hydrangeas, sprinkle dolomitic lime around the root zone (this is available at nursery outlets.)
    
Continue watering your camellias, gardenias and azaleas regularly; and mulch the roots with acid compost or leaf mould.  Do not feed now or the lush new growth produced will overwhelm the swelling flower buds.

Move indoor pot plants out of draughts and away from cold glass window panes; also many pot plants dislike being too close to heaters. Mist spray the leaves often and stand the pots on top of pebbles in a drip tray filled with water to help humidify the air.

Cymbidium and Phalenopsis orchids are spiking and starting to bloom so stake the flower spikes and feed and water regularly. If they are growing outdoors, bring them indoors when in bloom to enjoy their beauty. Dendrobium orchids need a cool, dry winter to induce flowers.

Broad BeansBroad BeansBroad BeansVegetables: Throughout the country, May is traditionally the month to sow broad beans. They germinate easily, and grow quickly into tall, upright bushes with stems reaching 1 to 2m tall, which will need some support. Do not sow too many seeds at one time, because one or two bushes will supply ample beans for the average family. For successive sowing, plant out every 3 weeks in autumn. Young broad beans can be cooked whole but mature pods need to be shelled before cooking. When they are in full bloom and the first pods begin to swell, nip out the growing tips to encourage fruit set. 

In very cold regions of the Highveld it is the end of the winter vegetable planting season, because the first frost can arrive in April or May. Your winter veggies should already be in the soil and reasonably well established, before the bitter cold arrives in June and July. If your seedlings are still very small, make a note to start sowing seeds earlier next year. In June & July many crops like beetroot and spinach seem to stop growing, this is also true of many hardy herbs, but if you have a small plastic tunnel, or can protect your crops with a frost cover at night, you can extend your growing season. Mulching the roots of your vegetables will also keep the soil warmer. In these regions it is important to water regularly, but not to overwater.

In the sub-tropical regions of KZN and Mpumalanga you can continue sowing traditional summer vegetables, as well as cool season crops like peas, cabbage, carrots, cauliflower, spinach, onions and turnips.

CauliflowerCauliflowerCauliflowerContinue to feed and water your winter crops regularly and remember that green, leafy vegetables require a nitrogen rich fertiliser.  In cold regions, lettuce does extremely well if planted during autumn and early winter; and in warmer regions it does well throughout winter; water your lettuce regularly to prevent it from going bitter. Root crops like carrots, turnips, parsnips and radish are best sown directly into the soil as they do not transplant well.

It is also time to sow peas, but in very cold regions delay sowing peas until late winter and early spring to avoid frost damage to the flowers. Peas can be sown every 3 to 4 weeks for a continual supply. Sweet peas and peas are good companion plants for each other - plant them together on a tepee for best results and a wonderful aesthetic appeal in the garden. Try some snow peas or sugar snap peas, for their tender and crisp pods.

For lovely white stems on leeks and celery blanch the stems as they grow by drawing the soil up against them. Store your lifted potatoes in a cool, dry and dark place for winter use. Check vegetables like broccoli, cabbage, kohlrabi and kale for aphids and hose them off with a jet of water, or spray them with soapy water. If snails are a problem, treat them with organic snail bait like Ferramol.

Fruit: Plant out soft fruits like raspberries and gooseberries in well-prepared holes, and at the same depth as they are in the bag. Remove all runners from your strawberry plants so the mother plant will produce fruit in early summer. Harvest the last of your late-fruiting apples and pears and feed the trees afterwards. Feed your avocado trees with organic 3:1:5 and mulch them with manure or compost. Feed your paw-paws with 3:1:5 and water it in well. Many citrus varieties ripen at this time and to keep them producing fruit, apply a moderate amount of nitrogen fertiliser on the surface of the soil around the trees, ensuring that you keep it well away from the trunk, and water it in thoroughly afterwards; it is also important to keep fruiting trees well watered; especially in the summer rainfall regions.

Ilex mitis berries. Picture courtesy www.newplant.co.zaIlex mitis berries. Picture courtesy www.newplant.co.zaIlex mitis berries. Picture courtesy www.newplant.co.zaIn dry, cold winter regions the birds will appreciate some water and regular feeding in winter; but you could help them even more by planting trees, shrubs and various grasses in your garden which will help to feed them during the tough winter months. For example, autumn and winter flowering aloes are a rich source of food for many bird species and the female trees of the following plants bear heavy crops of berries: Cape holly (Ilex mitis) bears crops of small red, holly-like berries in autumn and winter; White Karee (Searsia pendulina) produces small green edible fruits that ripen to a reddish colour in autumn and are relished by many fruit eating birds, including ground birds like guinea fowl; Red currant (Searsia chirindensis) bears heavy bunches of shiny, dark reddish-brown berries in late summer and autumn. Dogwood (Rhamnus prinoides) produces edible berries for the birds almost continuously throughout the year.

Summer rainfall (Temperate or Highveld Regions)

Gardens in these regions are ablaze with fiery orange blooms of wild dagga (Leonitis), aloes, red hot pokers (Kniphofia) and Cape Honeysuckle. Not to mention the glorious displays of Barberton daisies, bergenia, bush violet, ribbon bush, plectranthus and nerines. Acers and liquidambers are showing their autums glory and the oak-leaved hydrangeas (Hydrangea quercifiolia), Viburnum opulus and heavenly bamboo (Nandina domestica) also come into their own at this time of the year, so if your garden is looking dreary, visit your favourite garden centre to select a few of these. Ensure that you water your winter and spring flowering shrubs deeply and regularly;especially your azaleas, camellias and gardenias.

If you want a truly beautiful winter, spring and early summer garden brimming with flowers and vegetables, and you havent prepared yet, May is the last month to finish planting your winter bulbs, flowering seedlings, vegetables and winter herbs. In warmer regions you can still sow alyssum, calendula, candytuft, campanula, delphinium, linaria, California poppy, gaillardia, Namaqualand daisy, snapdragon, Bokbaai vygie, sweetpeas and Virginian stocks, but bear in mind that with lower night time tempertures, germination will be slower. In cold regions it would be wiser to purchase trays of seedlings from your garden centre, although sweetpeas seed can still be sown in May. Try trays of English daisy (Bellis perennis), calendula, cineraria, cornflower, delphinium, foxglove, gazania, Iceland poppy, larkspur, Bokbaai vygie, lobelia, lupin, pansy, penstemon, petunia, primula, schizanthus, and viola. If you have already planted your winter and spring flowering seedlings, water regularly and fertilise with organic 3:1:5.

In cold Highveld regions it is the end of the winter vegetable planting season, but in warmer regions you can still sow seeds of cool season crops like broad beans, peas, cabbage, carrots, cauliflower, spinach, onions and turnips. Sow a last batch of onions and plant out seedlings of broccoli, spinach, cabbage, kale, winter lettuce and leeks. Try sowing some oriental vegetables like mizuna, pakchoi and tatsoi, they are cold hardy and very healthy. In very cold regions wait until June or July to sow peas, because the leaves are frost hardy but the flowers are tender. Planting them later will ensure that they flower at the right time. Divide overcrowded rhubarb and asparagus plants this month. 

Make sure you have mulched and covered those tender shrubs; cut back on watering and only water in the morning to prevent frost damage. Store your hosepipe where it is protected from frost and bind water pipes with strips of hessian to protect them from freezing. Do not prune evergreen plants at this time of the year as all those branches and twigs will help protect your plants from the frost. Now is the best time to move cycads but do not overwater them once they have been transplanted, as this could cause them to rot. Stop feeding your lawn and set your blades on their highest level. Watch out for winter grass, Poa annua and pull it out immediately before it sets seed. Remember, evergreen lawns need watering throughout the year.

Winter rainfall regions (Mediterranean)

Gardens in this region are ablaze with the fiery orange flowers of wild dagga (Leonotis), falling stars (Crocosmia aurea) and bottlebrushes (Callistemon citrinus). Osteospermum, nerines and plectranthus also put on a glorious show now. Protea repens and Protea nerifolia have started blooming, as well as Halleria elliptica, and Cassia corymbosa.
 
April and May are the main planting times in the Western Cape, and when the dry season has been broken by the first winter rains, the soil is perfect to plant fynbos like restios, proteas, leucadendrons and ericas. Finish planting out winter and spring flower seedlings this month; for sunny spots try alyssum, delphinium, dianthus, Iceland poppies, statice,  Shirley poppy, nemesias, gazanias, godetia, pansy and viola, calendulas, ornamental kale, helichrysum and stocks; while for shady spots try aquilegia, Canterbury bells, nicotiana, cineraria, primulas and foxgloves. Nemesias are really worth planting because they are indigenous to the Cape and thrive in this region, despite their delicate appearance. May is also traditionally the month to sow sweet peas in the Cape.

May is a great time to trim shrubs in the garden, to allow some extra sunlight into the winter garden. Don’t forget to trim those alongside pathways, where brushing past the soaking wet bushes can be irritating in winter. Raise containers off the ground to prevent them from getting water logged; and remember to water areas of the garden under the eaves if the house and beneath south-facing walls and hedges, that do not receive rainfall. Check the acidity of your soil and if necessary apply dolomitic lime. Finish pruning your summer flowering shrubs and mulch your entire garden if you did not do so last month. Fertilise your winter and spring flowering plants regularly with organic 3:1:5. Put down Ferramol organic snail bait, it stops the snails from feeding and is safe to use around children and pets. Cover your compost heap to prevent it becoming too wet; and in areas which do receive frost, cover your tender plants this month.

Tidy up perennials like lavender, daisy bushes and geraniums; and when liliums have finished flowering, cut back the dead foliage and mulch the bulbs - don’t forget to mark where they are growing. Tulips are planted out at the end of May. Take hardwood cuttings of your plectranthus when they have finished flowering.

Autumn is a good time to plant lawn plugs and lay instant lawn. Remember that Kikuyu and Buffalo Lawn do not grow well in the shade and may rot in wet weather; plant Berea grass instead. Feed with Neutrog Bounce Back and bone meal, and apply a light top dressing. Allow your lawn to grow quite long before cutting and do not mow it too short; mow Buffalo lawn for the last time.

Sow your last crops of cabbage, Chinese cabbage, carrot, cauliflower, parsnip and Swiss chard; and continue sowing and planting broad beans, broccoli, leek, onion, parsley, peas, turnip, celery, radish, true spinach and beet. Various butter lettuce and spinach such as 'Virolay' do very well in the cooler autumn and winter months. If you have a shallow pond in full sun why not try growing some waterblommetjies (Aponogeton distachyos) for those delicious stews. They are indigenous to the winter rainfall regions and are very pretty with their long lance-shaped green leaves and scented white flowers in spring and autumn. They should be planted out now, either directly into the mud at the bottom of shallow ponds or dams, or into pots which are then submerged.

Dry, semi-arid and continental regions     

Make the most of the last warm sunny days to finish planting your winter and spring flowering seedlings, bulbs and vegetables before the cold winter winds move in; water and fertilise regularly. In gardens with poor sandy soil or clay, add as much compost as possible; and in heavy clay soil, raised beds work best. Now is the best time to move cycads, but do not overwater them once they have been transplanted as this could cause them to rot. Autumn is also a good time to plant out hardy trees and shrubs as these will be well established by summer.

Make sure you have mulched all planted areas thickly to protect against the cold. Do place mulch near plant stems. Cover those tender shrubs; try spraying them with Wilt-Pruf, which forms a protective coating on the leaves and protects against frost. Do not prune evergreens at this time of the year, all those branches and twigs will help protect your plants from the frost. Cut back on watering and only water in the morning to prevent frost damage; store your hosepipe where it is protected from frost. In brak water areas, allow the top layer of soil to dry out before watering; this will prevent the build-up of harmful salts in the soil. Remove all leaves from your rainwater tanks as they will spoil the water when they rot.

In gardens which haven't received their first frost yet the Chrysanthemums and red hot pokers (Kniphofia) will be in full bloom, and dahlias may be having their last flush of blooms, so continue watering and feeding these until the flowers have faded. In warmer areas you can cut your chrysanthemums down to about 20cm but in very cold gardens do not prune them until spring or early summer; transplanting is only done in October. Unpruned plants may look untidy but the extra foliage will help protect them from frost damage.

Aloes planted in flower borders amongst other plants often receive too much shade and water, making them susceptible to  rust, and if the days are still sunny and warm, powdery mildew can develop. Always position them in an open sunny position and avoid overwatering.

Do not cut your lawn now, as the extra length will protect the roots against the cold. Watch out for winter grass, Poa annua and pull it out immediately before it sets seed. Remember, evergreen lawns need watering throughout the year.

You can still sow fast maturing flowering seedlings like calendula, Bokbaai vygies, and Virginian stocks, but bear in mind that with lower night time temperatures, germination will be slower. For other winter and spring flowers, it would be wiser to purchase trays of seedlings from your garden centre. In very cold regions sweet peas are usually only sown in May and June to ensure that they bloom later, once the worst of the frost is over. Don’t forget some pansies and violas, they do well in these regions in winter and can be in bloom until late October.

Make a final sowing of broad beans and onions, and in warmer regions, plant out the last of your well established winter lettuce, true spinach, shallots, leeks and kohlrabi. In very cold regions wait until June or July to sow peas, because the leaves are frost hardy but the flowers are tender. Planting them later will ensure that they flower at the right time.

Subtropical summer rainfall regions

As winter creeps in many winter flowering plants are pushing out flower spikes, especially the erythrinas with their bright scarlet, nectar-laden flowers, which invites birds and monkeys to a feast. The aloes also start blooming now, so visit your garden centre and choose some for your garden - the drier the plants are the better they flower. The fiery orange spikes of wild dagga also adorn the landscape, and are also a favourite with bird. Gardeners in these regions look forward to a cool, reasonably dry period for the next four months; and May is prime gardening time in these regions, so get out there and have some fun; the garden centres are brimming with gorgeous shrubs, trees and seedlings to inspire you.

Roses are often at their best in May; so do not prune them now; continue to feed them with organic 3:1:5 and spray against fungal diseases. Feed all your flowering plants with organic 3:1:5; and because hot winds can dry out your beds quickly, mulch thickly and ensure that your plants are receiving enough water during these spells. Bougainvilleas will be at their most beautiful this month; feed them with organic 3:1:5 and water it in well; don’t feed them with a high nitrogen feeder as this will produce lots of leaves at the expense of the flowers. Cut down the spent flowering stems of heliconias and divide those that are overgrown.Re-pot your pot plants now if necessary. Plant out Litchi and Citrus trees now.

Prune evergreen shrubs to improve their shape; and once deciduouis trees and shrubs drop their leaves, it is an excellent time to prune because the bare branches make easier pruning for shape. Do not remove more than one-third of the branches of a tree at one time. May is the best time to transplant trees and shrubs and autumn is the best time to move cycads, but do not overwater them once they have been transplanted as this could cause them to rot. May is also an ideal time to repot both indoor and outdoor pot plants. Remove the plants from the pots and wash off as much of the old soil as you can with a hosepipe. Prune the roots if necessary before repotting with fresh potting soil; dont forget to provide drainage. A newly potted plant will do better if pruned lightly and if large unwanted leaves are removed. Keep in a cool place until the plant is settled.

Continue watering your lawn but cut back to about once every 10 to 14 days. This allows more surface area for the blades to catch light for photosynthesis, thus keeping the grass alive; and also encourages deeper roots. Feed for the last time with a fertiliser that is high in nitrogen, and do not mow too short. 

Cymbidium and Phalenopsis orchids are spiking and starting to bloom so stake the flower spikes and feed and water regularly. If they are growing outdoors, bring them indoors when in bloom to enjoy their beauty. Dendrobium orchids need a cool, dry winter to induce flowers.

May is the correct time to plant out pansies and violas in these regions, because if you plant too early, when the soil temperatures are still too hot, results can be disappointing. Plant corms of anemones and ranunculus this month as well as nasturtiums and marigolds for quick colour. Sow and plant alyssum, verbena, snapdragon, sweet pea, stocks, delphiniums, dahlia, salvias, impatiens, begonia, petunia, portulaca, alyssum, aster, dianthus, foxgloves, cineraria, gazania, phlox, calendula, lobelia, primulas, marigold, nicotiana, zinnia and torenia.

May is a wonderful month to plant an herb and vegetable garden. Try herbs like oregano, Basil, lemon grass, Parsley, thyme, rocket, fennel, dill and mint, to name a few. Plant out chives, garlic and asparagus crowns this month. Peas, broad beans and lettuce can be sown at the end of May as well as potatoes. Sow or plant green beans, baby marrows and other squash and pumpkin varieties as well as cabbage, tomatoes, cucumbers, peppers, eggplants, Swiss chard, carrots, beetroot, turnips, onions and leeks.

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