May Gardening Tasks

‘Winter is coming.’ The now-famous line from Game of Thrones is also true of gardening, so get your seeds sown: Namaqualand daisies, bokbaaivygies, Virginia stocks and linarias. And obviously plant your daffodil bulbs! Don’t miss out on this window of opportunity to get your garden prepped, knowing that in a little while you and the insects, bees and birds will be rewarded with racetracks of bursting colour!

General Tasks

  • Ensure that tender plants are protected, as frost can strike as early as May. Move frost-sensitive plants in pots to a protected place and buy frost-guard material to protect sensitive plants in the garden.
  • Use autumn leaves as mulch to keep the soil warm, protect soil microorganisms, and protect the roots of tender plants.
  • Move wormeries into a sheltered, warm area.
  • Sow green manures in beds that will be fallow during winter.
  • Water camellias, azaleas, rhododendrons, and magnolias regularly and mulch with acidic compost.
  • In the winter-rainfall regions, clean up gutters, downpipes, and drainage channels, right down to the stormwater drains in the street in front of your house to prevent flooding.
  • Falling leaves can clog up ponds. They sink to the bottom, decompose, and cause harmful by-products. Clean them up, and to prevent them from falling in the water you can place fine mesh netting across the top and secure the edges with bricks.
  • Cymbidium orchids and cyclamens will be coming into flower now. Both require humidity from a frequent misting on their leaves. If you give them a weekly deep watering, take them out of their display pots and to the kitchen sink for a dunking. Let them drain off well before displaying them again.

READ MORE: We have some tips for preparing for frost, fighting frost as well as ways to protect your plants from frost.


  • Sow some wild grass seed somewhere in your garden to encourage birds in winter. These seed mixes are available in seed packets at most outlets selling flower and vegetable seed.
  • In temperate climes, calendulas, nemesias (wild snapdragons), gazanias, Namaqualand daisies, bokbaaivygies and Virginian stocks can still be sown directly into prepared soil and will germinate in no time.


  • Plant more seedlings of: snapdragons, Bellis perennis, lobelias, primulas, phlox, Iceland poppies and petunias.
  • Fill up window boxes to get them ready for spring. Use perennials like gazanias, geraniums, diascias and osteospermums, and add pansies, violas, and primulas too.
  • The dry winter climate in summer-rainfall regions is perfect for petunias, as they don’t like too much rain on their flowers.
  • Team up flowering kale and lobularia (alyssum) as a lovely border for a shrub bed. The lobularias, just like the kale, are very cold resistant and at their best behaviour in winter.


  • You can still plant your winter- and spring-flowering bulbs. These include daffodils, freesias, anemones, hyacinths, Dutch irises, ranunculus, muscari, chikerinchees, babiana, ixias and sparaxis.
  • Water newly planted bulbs deeply every four days – they should never dry out completely. Those in pots will need more regular watering.
  • If your bulbs have started coming up, you can start feeding with bulb food.
  • Plant a few hyacinth bulbs for indoor aroma and colour. Plant the bulbs in moist, quality potting soil in a shallow bowl and place in a dark cupboard until the flower spikes break ground.
  • Cut back any summer bulbs that have died off. Mark the spot where they are planted so as not to dig them up accidentally.
  • If you want to grow some tulips, order them now directly from bulb growers and plant them as soon as you receive them.


  • Feed Sweet peas every fortnight.
  • If your pansies are not growing all that well, feed with a fertiliser that has trace elements like Trelmix or Seagro.
  • Bougainvilleas are at their best now; feed them with organic 3:1:5 and water well afterwards.
  • Aloes need feeding too – add a layer of old kraal manure or compost around their stems.


  • Something in the wrong place? Now is a good time to move established shrubs and trees to a different spot. Transplanted roses or any other shrubs must be drenched afterwards with a liquid fertiliser to avoid transplant shock.

READ MORE: If you need tips for planting trees, try this step-by-step guide.

Plant Cuttings

  • Take hardwood cuttings of trees, shrubs, and climbers – root them with hormone powder in a mix of damp river sand and compost and keep in a protected place.
  • Plants that can be propagated by hardwood cutting include ‘Iceberg’ roses, Viburnum opulus ‘Roseum’, Nandina domestica, frangipani, wisteria, crepe myrtle, hydrangea and berberis, as well as fruit trees such as figs, pomegranates, quinces and mulberries.


  • Cut dahlias back to ground level and dig up the rhizomes to store them. For best results, clean them up and dust with a fungicide powder before storing in a cool and dry place.
  • Continue to disbud young annual seedlings to prevent them from flowering while still too small. This directs the plants energy into plant growth instead of flower growth.
  • Neaten up perennials like Michaelmas daisies, obedience plants, penstemons, yarrow, Gaillardia (blanket flower) and chrysanthemums which will stop flowering at the end of this month.
  • Prune back plectranthus after flowering and use the clippings as cutting material to grow more plants. They root very easily if kept in a lightly shaded spot protected from cold. Add a layer of compost around their root areas.
  • Hellebores will be sprouting new foliage, so you can remove the old, tatty leaves and give them a fresh layer of compost. They will soon be in flower.
  • Cut canna stems and leaves off at ground level and use this material as a mulch over the top of the rhizomes.


  • Mow lawns with the blades set high and water when dry.
  • You can still do a last over-seeding with ‘All Seasons Evergreen’ or ‘Shade Over’.
  • Use a pre-emergence weed killer to kill of winter grass in the lawn and in paving.
  • Rake fallen leaves off the lawn to prevent them from blocking out sunlight and place them on the compost heap.
  • To improve drainage in lawns before the (hopefully) heavy winter rains in the Cape, spike deep holes with a sharp garden fork all over the lawn. Fill in the holes by brushing in sharp river sand or old potting soil. Supply a dressing of bonemeal or superphosphate to improve root growth. Now is also a good time to lay instant lawn sods or to over-seed damaged areas.


  • Snails will be looking for places to overwinter. Clean under containers and in clumps of perennials, where they will huddle together. Use eggshells around your plants to deter them or put out organic snail bait amongst young seedlings if you have an infestation.
  • Scale is a sap-sucking insect that can infect the stems and leaves of indoor plants, eventually killing the plant. Curb scale by keeping plants clean from dust, in a humid spot and feed regularly. Remove scale by wiping off the leaves and stems with a damp paper towel or cloth dipped in a little dishwashing liquid. If heavily infested, rather completely remove infested parts of the plant. You can also use an organic insecticide that is safe to use indoors.

Rose Tasks

  • During May and June, rose care tasks can be kept to a minimum as the rose season is starting to wind down.
  • Roses that have been well cared for through regular watering, spraying, and fertilising should still be flowering well and covered with green leaves. There is no need to pamper plants that are not looking good – just allow them to go naturally dormant.
  • Reduce watering to once a week or once every two weeks, except roses in the Lowveld and tropical KwaZulu-Natal with lush growth and flowers. They require more regular watering for flowering into winter. You should also fertilise your roses this month if you live in these areas.
  • Continue spraying with an organic fungicide and an organic insect spray to protect the new growth from black spot, powdery mildew, rust, and downy mildew, which are far more prolific in cooler weather.
  • Maintenance is not as arduous, because blooms and buds on the rose bushes take much longer to open and fade at this time.
  • As this is the last rose flush, roses can be cut to use inside the home without concern about the quality of the next flush.
  • Roses can be transplanted from mid-May to mid-June. month to transplant roses that are in the wrong position. Label bushes before you start as it will be hard to identify the different varieties once they are cut down and the blooms removed. Trim the rose by a third, cut around the roots with a spade pushed deeply into the ground and lever out carefully. Replant the rose immediately in well-prepared soil. Water well immediately and thereafter once a week.

May Veggie Sowing Guide

Highveld and KwaZulu-Natal Midlands

Broad beans, kohlrabi, radishes

Middleveld (Pretoria and other less frosty areas)

Broad beans, lettuce, garden peas

Eastern Cape and Little Karoo

Broad beans, onions, garden peas, radishes

Western Cape (and Southern Coast)

Broad beans, celery, lettuce, leeks, onions, garden peas, radishes, spinach, turnips

Northern Cape and Great Karoo

Broad beans, onions, spinach, turnips

Lowveld and KwaZulu-Natal coast

Broad beans, bush beans, runner beans, beetroot, brinjals, cabbage, carrots, cucumber, kohlrabi, leeks, lettuce, parsnips, peppers (sweet peppers and chillies), garden peas, pumpkins and Hubbard squash, radishes, rhubarb, spinach and Swiss chard, bush and trailing squashes, tomatoes, turnips

Veggie Garden Tasks For May

  • The first frost usually occurs towards the end of May. Use frost cloth to cover tender leafy veggies when frost is predicted. Cover them in the afternoon and remove it the next morning.
  • Harvest comfrey, borage, or yarrow leaves before they go dormant for winter. Add leaves to the compost heap as compost activators.
  • Use fallen leaves as a light mulch around growing veggies. This protects the soil life from the cold and helps retain moisture.
  • Grow edible flowers like pansies and violas as a colourful border around veggie beds.
  • Remove small unripe fruit (tomatoes, brinjals, squashes etc.) so that the plant can put its energy into ripening the larger remaining fruit.
  • Water at least once a week, depending on the temperature and sunshine. Water in the mornings to ensure your plants are dry before the evening cold sets in.
  • Summer veggies that are over but not diseased can be dug into the soil to build up its organic content.
  • Earth up the soil around Brussels sprouts, cabbages, cauliflower, and broad beans to support the stems.
  • Keep lettuce moist and sweet with regular watering.
  • Feed brassica other seedlings with a liquid fertiliser to strengthen them for the cold weather ahead.
  • Plant nasturtiums close to brassicas as a trap crop for aphids.
  • Watch out for aphids on all brassicas, especially kale and cabbage, and spray infested plants with an organic or biological insecticide.
  • Add rows of ornamental flowering kale between winter vegetables. Good winter companion plants for kale in general are beets, marigolds, onions, nasturtiums, and spinach.

READ MORE: Whether you are a beginner or an experienced gardener, there are always questions when it comes to growing veggies. We have answered some of those questions for you, check it out.


Keep your tender plants warm by making a cold frame, see how we made it using an old window.

Check out this article to learn how you can make your own worm farm.


As the weather gets colder, soup becomes an appealing dinner idea. Try out these recipes and find the perfect soup and bread combination.

The Gardener