May in the Garden

The mild month of May is a perfect time to add new plants to your autumn garden. Plant some winter and spring beauties on ‘Workers’ Day (you will be at home on the public holiday on 1 May!) and see how smart plants can ‘work’ for you in the seasons to come…

Trending – ‘Colour blocking’

Colour blocking is a fashion trend which originated from the artwork of Dutch painter, Piet Mondriaan. He used clean, and simple lines, and solid colours opposing each other on the colour wheel. This trend works very well in the garden too, if you plant bold patches of opposing, but complementary colour combinations. An example: blue delphiniums paired with bright orange calendulas. You can even add a little grey in there by using bold swathes of silvery grey sedge grass (Festuca). Midnight blue and bright yellow is another good combination and you can do this by planting a mass of dark blue pansies set off by bright yellow violas. If you’re not sure about this concept, visit a top GCA garden centre’s seedling tables and flowering perennial displays (many indigenous daisies, diascias and nemesias are flowering now), where you will clearly see which colours go together well. Colour blocking doesn’t stop with plants – you can paint a background wall in a contrasting, but complementing colour, to the plants near it.

Spoil mom!

Mother’s Day is on Sunday 13th May. As moth orchids (Phalaenopsis) are always available in bloom and stay that way for months on end, why not spoil your mom or grandma with a beautiful specimen to keep her company with its floral elegance throughout winter? You will find the widest variety and healthiest specimens at your nearest GCA garden centre. They will also have smart cover pots in stock to display it in.  

Smart planting

Heavenly bamboo (Nandina domestica) is the heavenliest, ‘fake bamboo’ available! In large pots, they mean good luck at your front door and they are the ‘zen’ in Zen gardens. You can plant them in a row in the narrow space, with its changing sun and shade patterns between the house and a boundary wall. They will soon supply a lacy look with their rust-tinted leaves in the cold months, small white flowers in spring, and post box red berries in autumn. They will grow heavenwards with their slender and tall branches, giving you privacy, while their roots are not dangerous.  

Camellia (Camellia japonica) – large evergreen shrub or small tree with glossy, dark green leaves. Suitable for shade or sun (not baking hot!). Very cold and frost hardy, and truly not a water guzzler when established. They produce masses of the most beautiful and delicate flowers from late winter until spring. Many hybrids with different flower shapes are available in an array of colours from pure white, to all shades of pink and red.     

Pork bush (Portulacaria afra) – not really known as a low hedge plant but one of the best indigenous plants to put to this use, as it does not mind being pruned frequently and can do the job of being a barrier perfectly in a dry garden. It is extremely drought resistant and fast-growing. Once established, it will basically look after itself.

New Zealand Flax (Phormium) with their long, leathery, sword-shaped leaves that are held in fans emerging from fleshy roots, always make a bold statement in the garden and there are many hybrids in a wide array of foliage colours to choose from. They thrive in full sun or dappled shade and can withstand a fair amount of winter cold, although some hybrids can be damaged by frost. A little protection with frost cover can overcome this. GCA garden centres report that the following two hybrids are amongst their top sellers:

  • tenax Rubra’ – a well-known, cold-hardy cultivar with a graceful, arching habit with a cascade of narrow, deeply bronzed foliage.
  • Fire Chief’ – Upright growth habit with rich crimson red leaves with darker red margins. Full sun intensifies the foliage colours.

Jade plant (Crassula ovata ‘Red Edge’) – the jade plant is probably the most widely grown succulent in gardens as well as containers. Spectacular forms are found in nature and selected for the nursery trade such as ‘Red Edge’ with bright green fleshy leaves with red margins. This fast-growing succulent produce a mass of star shaped flowers in winter and is a very attractive rockery or accent plant for dry gardens. Very cold and drought resistant.

Naturalising spring bulbs

To create a most spectacular spring meadow and to enjoy the beauty of a wider range of veld flowers every year, look out for the following perennial bulbous plants:

Blue Stars (Aristea major) – handsome structural plant with blue flowers

Flames (Chasmanthe floribunda) – perfect for mass planting, orange flowers

Weeping Anthericum (Chlorophytum saundersiae) – grass-like with masses of starry white flowers for sun or light shade

Fortnight Lily (Dietes bicolor) – sun or light shade, lots of yellow flowers with brown eye

Red-hot poker (Kniphofia praecox) – tall, striking spikes of yellow/orange flowers

Sweet garlic (Tulbaghia fragrans) – sweetly scented, long lasting mauve flowers

Bush Lily (Veltheimia bracteata) – attractive, glossy green foliage and long spikes of dusky pink flowers for light shade

Watsonia borbonica ‘Pink’ – very decorative spikes and excellent cut flower

White Arum Lily (Zantedeschia aethiopica) – creamy white spathes and large showy leaves for moist, shady areas

Bedding bestie

Our bedding bestie for May is stocks (Matthiola incana) – one of the most romantic winter and spring flowering annuals to plant. Foliage is soft and velvety greyish green, and the densely packed flower spikes are extremely fragrant (available in shades of dark purple, rose, cream, pink, and white). There are some secrets to growing them successfully:

  • Never plant them in a bed where they have previously grown
  • Prepare the soil with ample compost, general fertiliser like 2:3:2, and a light dusting of lime
  • Space the seedlings about 35cm apart
  • Do not handle them by touching their stems, rather handle them by the leaves. Keep well-watered, but don’t overdo it.

Enjoy a good cut flower!  For more info on stocks, click here.

Rose care for May  

  • Keep on spraying against fungal infections like black spot, mildews and rust which are much more active in cooler weather.
  • Aphids can still be problematic and more difficult to destroy in summer, seemingly due to higher sugar levels in the plant cells, which attracts them. Use systemic insecticides as sprays or soil drench.  

Pruning to do

  • Prune plectranthus species and varieties as soon as they have stopped their autumn-flowering.
  • It is best to wait for the first frost to arrive and then cut off the dead frosted top growth of dahlias.
  • Chop chrysanthemums down to encourage bushy growth.
  • Cut back Japanese anemones, Michaelmas daisies and daisy bushes.

Pest watch

Conifer aphids which cannot be seen by the naked eye, become active from May to September. Damage done like yellowing foliage, shoot dieback and the eventual demise of the whole plant, can only be seen after the end of winter. Preventative treatment is therefore recommended from May to September, by applying systemic granular or liquid insecticide every two weeks. Drench the soil if a liquid formulation is used, or spread granular insecticide over the rooting zone into the soil, and water in well afterwards.

Inland gardening
(Gauteng, Free State, North West, Mpumalanga and Limpopo)

  • Water newly planted bulbs deeply every four days – they should never dry out completely. Those in pots will need more regular watering. You can still plant all spring-flowering bulbs like daffodils, ranunculus, and more.
  • Also 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 untiltheflower spikes break ground.
  • 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.
  • Hellebores, those old stalwarts in cold gardens, 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.
  • Plant the seeds of sugar snap peas in a circle to grow them up a cane tepee. Also plant a patch of peppery edibles by alternating rows of tatsoi, rocket, radish and pak choi.
  • Cut down the last tomatoes, bring the unripe fruit indoors and place with a banana to ripen fully.
  • Start covering plants against frost at night.
  • Plant more seedlings of: Snapdragons, Bellis perennis, lobelias, primulas, phlox, Iceland poppies and petunias.
  • Mow lawns with the blades set high and water when dry. You can still do a last over-seeding with some seed types. Visit your local GCA to see which one will be the best for you.

Coastal gardening
(Western Cape, Northern Cape, Eastern Cape, and KwaZulu-Natal)

  • Now is a good time to lay instant lawn sods or to over-seed damaged areas.  
  • If your plants are not doing well it is probably due to poor soil and the aftermath of drought. Invest in a bulk load of compost to add to all planting areas. Do not dig it in, just spread it out on the surface to be gently worked in by micro-organisms. Keep thick layers of compost away from the main stems of plants, as it can cause rotting.
  • Sprouting is a fast and fun way to grow healthy edibles on a window sill. Sprout some mung beans, chickpeas, lentils and Alfalfa to use in salads and stir fries.
  • For micro eating, sow a mix of salad greens, radishes, baby spinach and beets thickly in a window box. Snip off the germinating young stems and leaves to use on sandwiches, or in your daily smoothie.
  • Fill up window boxes and hanging baskets to get them ready for spring. Use perennials like gazanias, geraniums, diascias and osteospermums. Add pansies, violas and primulas in there too.
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