August Gardening Tasks

With the passing of the longest night and shortest day now behind us (thank goodness!), there are only good things to come! August is the month to do all your spring planning which sounds daunting, but we promise it’s not. Here is a list of August gardening tasks to help you.

General Tasks

Don’t be in a hurry to remove the frost covering on frost-sensitive plants.
Wash seedling trays with hot water and bleach.
August is a windy month in most parts of South Africa, so don’t forget to check the stakes of newly planted trees and standards like roses to prevent them from toppling over or snapping in the wind.
Prepare beds for spring planting. Dig in compost, bonemeal and slow-release organic fertiliser.
Water more often as the days get warmer. If the soil is moist, delay watering by a day or so.
Cover soil with a thin layer of mulch to encourage earthworms.
Don’t be tempted to prune frost-damaged plants even if they look sad, just yet. Pruning now will encourage soft new growth that will be killed off by late frost.

Sowing

Start sowing hardy summer-flowering annuals in prepared seed trays. It is a cheap way to ensure colour in your borders and beds. Sow seeds of ageratums, cosmos, lobularias, cleomes, godetias, lavateras, marigolds, phloxes and nicotianas now. Keep the soil just moist until germination and the seed boxes protected from cold spells.

Planting

If your soil is very alkaline, you can sow and plant the following for your summer garden: California poppies, campanulas, dianthuses (pinks), irises, kangaroo paws, lavenders, sages, rosemaries, westringias and thymes.
Give aromatic indigenous shrubs that start flowering in winter and early spring a chance in your garden and the birds and bees will love it. They are the Buddleja species – saligna, auriculata and salviifolia – all with greyish-green foliage and sweetly scented masses of flowers.
Plant pelargoniums in garden beds, window boxes, pots and hanging baskets. They will flower from spring to autumn.
Winter seedlings that have finished flowering or need complementing with more colour can now be replaced or supplemented with spring and early summer annuals.
Look out for the following flowers at garden centres: petunias, calibrachoas, primulas, alyssum, dianthus, calendula, nemesias, snapdragons, foxgloves, lobelias, verbenas, impatiens, marigolds, pansies and violas.

Bulbs

At the end of August, you can start planting summer-flowering bulbs like gladiolus, calla lilies, dahlias, cannas, spider lilies, George lilies, tuberoses, galtonias, schizostylis, liatris, crocosmias, eucomis and storm lilies.

Feeding

Feed winter-flowering bulbs that are dying down, with specialised bulb food. This specialised fertiliser can also be used to feed summer bulbs in the garden as well as those you grow in pots like amaryllis.
Start feeding hydrangeas with acid-loving plant food – a specialised fertiliser for blue flowers.
Feed tropical as well as deciduous fruit trees with a formulation high in potassium like 4:1:6.
Feed roses after pruning with a specialised formula for roses to enhance lush foliage, bud formation and colour like 8:1:5.
Plants like azaleas, gardenias, brunfelsia and lemon trees, sometimes need a spring boost with a trace element water-soluble product to correct yellowing and blotching foliage. Follow up afterwards with a general fertiliser for fruit and flowers.
Revive focal container plants (which do not need re-potting yet) by removing the top layer of old potting soil and replacing it with a mix of fresh potting soil and compost. Feed it with a slow releasing general fertiliser, water well afterwards and add a layer of mulch.
When preparing new areas for planting in a bed, dig one bag of compost and a root builder like superphosphate or bonemeal into every 2m2 of the bed.
A growth stimulant containing fish emulsion is essential to have around to give seedlings and newly rooted cuttings a boost before they are planted out into the garden.
Fuchsias in the garden can be given a dressing of nitrogen-rich fertiliser, and those in pots can be re-potted into fresh potting soil. Supply a mulch around the plants and start pinching out the growth points to encourage bushy plants with lots of flowers.

Dividing and replanting

Time to think of dividing overgrown flaxes, ornamental grasses, lilyturfs, ajugas, agapanthuses and daylilies.
Lift and divide overgrown herb clumps.
You can divide guzmanias that have formed pups. Learn how to divide guzmanias here.

Pruning

Early spring is the perfect time to prune woody shrubs, especially foliage plants that are not influenced by a specific flowering season. They will regrow fast as the temperatures start rising.
Ornamental grasses should be cut back to soil level this month to encourage them to come back with new blades and flowering plumes in summer. Cut back muhly grass, ngongoni grass, pennisetums and Mexican feather grass.
Learn more about pruning in August here.

Lawns

A spring lawn treatment will help you create a perfect summer lawn, learn more in this article.

Pests

Snails and slugs will give it their best shot to feast on all your soft new spring plantings. Do battle with them by putting out snail bait, but also plant barrier plants like mint, garlic, chives, geraniums, foxgloves and fennel, which these pests hate, around susceptible plants.
Look out for aphids on new plant growth. Control with an organic insecticide.

Rose Tasks For August

In most areas, complete the pruning by the first week of August. In very cold areas delay pruning can be done at the end of August. After pruning, dig compost and other organic material into the soil around the roses and fertilise.
Tidy up climbing roses. Untie the canes and remove any old growth, keeping the strong, newer canes as the framework. Tie up and cut back side stems by 10 – 20cm.
Thrips is the biggest spoiler of rose blooms and new growth. For long-lasting action, drench the soil around each rose with Koinor by end August to prevent the thrips from hatching and spreading. Koinor also controls aphids.
Roses that were not fertilised in July, should be fertilised this month, otherwise fertilise in mid-September with Vigorosa.
Wait until the soil warms up towards the end of August before adding new mulch around the roses.
Water at least once a week in summer rainfall areas and increase it to twice a week as it gets warmer.
In winter rainfall areas protect new growth from fungal diseases by spraying with Chronos or Rose Protector.

August Veggie Sowing Guide

Highveld and KwaZulu-Natal Midlands

Bush and runner beans, beetroot, summer cabbage, capsicums, carrots, lettuce, garden peas, parsnips, radishes, rhubarb, spinach, Swiss chard, turnips.

Middleveld (Pretoria and other less frosty areas)

Bush and runner beans, beetroot, summer cabbage, carrots, cucumber, lettuce, marog, mealies, melons, parsnips, pumpkins, radishes, rhubarb, spinach, Swiss chard, turnips.

Eastern Cape and Little Karoo

Beetroot, summer cabbage, carrots, cucumber, lettuce, parsnips, marog, radishes, rhubarb, spinach, Swiss chard, turnips.

Western Cape (and Southern Coast)

Beetroot, carrots, lettuce, mealies, parsnips, garden peas, radishes, rhubarb, bush and trailing squash, Swiss chard, turnips.

Northern Cape and Great Karoo

Bush and runner beans, beetroot, carrots, lettuce, mealies, peas, radishes, rhubarb, spinach, Swiss chard, bush and trailing squash, tomatoes, turnips.

Lowveld and KwaZulu-Natal coast

Asparagus, Bush and runner beans, brinjals, capsicums, carrots, cucumber, marog, mealies, melons, pumpkins, radishes, bush and trailing squash, Swiss chard.

Veggie Garden Tasks For August

Mulch around veggies to keep the soil moist.
Increase watering as day temperatures rise. Water in the morning or at midday.
Prepare beds for spring and summer veggies by digging in compost or well-rotted manure, bonemeal and an organic fertiliser.
Feed cabbage, kale and other leafy greens with a nitrogen-rich liquid fertiliser or a granular fertiliser and water well afterwards.
Turn the compost heap and if it is dry, moisten with a light watering. This will speed up the decomposition process.
Water broad beans regularly so that the soil remains consistently moist.
Cut asparagus down to the ground. If necessary, divide asparagus and rhubarb crowns and replant.
In frost-free areas, continue sowing summer veggies but in cold summer- or winter-rainfall areas wait until day temperatures are consistently between 18°C – 21°C before starting with root vegetables.
Order and plant seed potatoes and garlic.
Plant out garlic cloves in fertile, well-composted soil in a semi-shaded bed. Cover cloves with about 3cm of soil.
Give veggies a once-a month drench with a liquid fertiliser or tonic. Liquid fertilisers are taken up quicker than granular fertilisers during cooler months.
Sow beetroot in beds where cabbage or other brassicas, lettuce or peas were grown.