September Gardening Tasks

It may still be a little chilly but by September, you know that spring has arrived! The days are getting warmer and longer, and the garden will soon be full of colour and sound. It’s a BIG gardening month and so if you need a reminder of what to do this month, check out our list below.

General Tasks

Water seedbeds and seedlings every day. Use a watering can with a fine rose that will not wash away the seedlings.
Cold and rain (in winter-rainfall areas) tends to compact the soil. Spread a 3 – 5cm layer of compost over the bed and gently fork it into the soil, then cover with a layer of mulch to encourage earthworm activity.
Refresh, top-up or replace pebbles and gravel around the garden, especially between paving stones where dust and mud accumulate to spoil the effect.
Clean out stale water from the urns of bromeliads
Keep up with weeding from early in the season as one year’s seeds can become seven year’s weeds. Mulching will help to suppress weed growth.

Sowing

Buy some bulk packs of Lobularia (alyssum or honey flower) and sow the seeds, which germinate fast and easily, all over your garden.
September’s weather is anything but predictable, so it is safest to start slowly, by planning and buying your seed first so that you are ready to sow when soil temperatures start to rise.

Planting

Plant charming perennials for bold patches of spring colour – Aquilegia hybrids (columbines), Geranium incanum (carpet geranium), Diascia hybrids (twin spur), Felicia amelloides, bearded irises, Scabiosa columbaria ‘Butterfly Blue’ (cornflower), Argyranthemum (marguerites or daisy bushes), salvias, gauras, giant statice and sweet violets.
Many indigenous perennials and groundcovers flower profusely in gentle spring weather. Most of these old favourites have been hybridised intensely to enlarge the range of Arctotis (African daisy), Diascia (twin spur), Gazania (treasure flower) and Osteospermum (Cape daisy) available.
Start planting begonias and impatiens in shade and sunpatiens in sun.
Plant the four P’s of spring, pansies, poppies, primulas and petunias. Read more about them here.
Plant Leucanthemums, Nemesias and Dianthus.
Clivias are in flower now. Visit your local nursery and clivia shows across the country to buy more plants to brighten up your shade garden. Don’t be tempted to divide existing plants too often as the clumps prefer to be left undisturbed for years.

Bulbs

You are not done with bulb planting, as the summer-flowering bulbs are now on sale. Start planting coloured calla lily hybrids and dahlias.

Feeding

Azaleas, camellias, hydrangeas, gardenias and brunfelsias must be fed with an acidic plant food and given a fresh layer of mulch that includes bark chips.
Fertilise the rest of your plants like crazy, this is the most important spring chore. Select the appropriate fertilisers and apply at the recommended rate. Keep granular fertiliser away from the stems of plants and always water thoroughly after application.

Dividing and replanting

Divide and re-plant Zantedeschia aethiopica (white arum lily) into boggy areas of the garden and on the southern side of the house. Learn how to do it here.
Remove some of the suckers from bromeliads to plant elsewhere to start a new patch of these wonderful plants.

Plant Cuttings

Take cuttings of favourite foliage plants like acalypha and crotons.

Pruning

By the end of September, you will be able to prune away the frost-damaged parts of affected plants to tidy them up and encourage new growth. Give them all a feed afterwards with a slow-release fertiliser, mulch well with a fresh layer of compost and water deeply.
Enhance the flower power of some tall-growing perennials that have been dormant in winter by pinching out the main stems when they have emerged again and are about 20cm high.
With rapid growth now, hedges, topiaries and standards will lose their shape. Rather clip regularly and lightly than give them one occasional drastic hack. The best way to keep the shape of a flowering standard is to regularly pinch out the growing tips of stems and wait until after each flower flush to give it a good clipping.
Prune hibiscuses and poinsettias and other winter-flowering shrubs.
Get more help for what to prune in spring in this article.

Lawns

Never use garden soil or so-called ‘topsoil’ for top dressing after spring scarifying an existing lawn, as it can cause bad drainage or could be infested with dormant weed seed. Rather invest in sterilised commercial lawn dressing, which will be in stock at garden centres.
Start training your lawn to be water-wise by watering it deeply only once a week – this will encourage deeper root growth.
Never cut your lawn too short as this keeps the roots near the surface where they are more likely to dry out.
For new lawns, start preparing the ground with compost and bonemeal before sowing seed or laying instant turf.
If weeds are a problem in large lawn areas treat them with a broadleaf herbicide. For smaller lawn areas use a ready-to-use broadleaf herbicide.
Check out our four point spring lawn plan here.

Pests

Snails become active as it gets warmer and can wipe out newly germinated seedlings overnight. Do a quick daily snail and slug check in the evenings. Use an organic snail bait or mulch with dry egg shells around plants to keep them protected.
In warmer weather, keep an eye out for invasions of lily borers in plants like clivias, arums and agapanthus, which can cause huge damage and kill off the plants. As they feed, the yellow-and-black striped larvae tunnel deep into the centres of the plants. Holes and prominent tunnel marks in the leaves are an indication of their presence. Catch them by hand to kill them or use a contact insecticide. This pest usually causes damage from September to April.
Look out for aphids on new plant growth. Where there are aphids, you’ll most likely find ants too as they have a symbiotic relationship. Ants protect aphids and aphids in turn provide the ants with honeydew. So you will also need to treat the ants.

Rose Tasks for September

The roses are growing fast and need plenty of water to develop new shoots and good flowering stems. Deep watering two or three times a week is necessary. This can be reduced later when growth slows down after the October flush.
Cover rose beds with a 5cm layer of mulch to keep the soil moist and reduce evaporation.
Fertilise by mid-September.
Prevent powdery mildew, aphids, thrips and beetles by spraying with an organic insecticide from mid-September.
Gardeners in winter-rainfall areas should spray with a fungicide to prevent black spot.
Extend the flowering period of hybrid tea roses by removing the tips of a third of flowering shoots from mid-September in highveld areas. Do this a week later in the Western Cape and Bloemfontein, and two weeks later in the Eastern Free State.
If the soil was not improved after pruning, dig in organics (including compost) to a depth of 30cm. This allows water to easily reach the roots. Drench after digging.
If a rose has not produced any new basal stems, pinch off all the tips. This encourages strong new flowering shoots.

September Veggie Sowing Guide

September’s weather is anything but predictable, so it is safest to start slowly, by planning and buying your seed first so that you are ready to sow when soil temperatures start to rise.

Highveld and KwaZulu-Natal Midlands

Bush and runner beans, beetroots, brinjals, cabbages, carrots, capsicums, cucumbers, celery, lettuce, marrows, mealies, melons, parsnips, peas, pumpkins, radishes, rhubarb, spinach and Swiss chard, squashes, turnips, tomatoes.

Middleveld (Pretoria and other less frosty areas)

Bush and runner beans, beetroots, brinjals, cabbages, capsicums, carrots, cucumbers, celery, lettuce, melons, mealies, parsnips, pumpkins, radishes, rhubarb, spinach and Swiss chard, squashes, turnips, tomatoes.

Eastern Cape and Little Karoo

Beetroots, brinjals, cabbages, carrots, capsicums, cucumbers, celery, lettuce, melons, marrows, mealies, pumpkins, radishes, rhubarb, spinach and Swiss chard, squashes, tomatoes.

Western Cape (and Southern Coast)

Runner beans, beetroots, brinjals, carrots, capsicums, cucumbers, celery, lettuce, melons, mealies, parsnips, pumpkins, radishes, rhubarb, Swiss chard, squashes, turnips, tomatoes.

Northern Cape and Great Karoo

Bush and runner beans, beetroots, brinjals, capsicums (start indoors), carrots, lettuces, mealies, peas, radishes, rhubarb, spinach and Swiss chard, bush and trailing squashes, tomatoes, turnips.

Lowveld and KwaZulu-Natal coast

Asparagus, bush and runner beans, brinjals, capsicums, cucumbers, mealies, and radishes.

Veggie Garden Tasks for September

In early September sow beetroots, carrots, cabbages, lettuce, peas, spinach and Swiss chard, which all germinate at lower soil temperatures. You can also plant seed potatoes
By mid-September sow bush and runner beans, zucchini, patty pans and Swiss chard.
By the end of September it is safe to sow tomatoes, brinjals, chillies and sweet peppers, mealies, pumpkins, melons and other trailing squashes.
At this time of year nurseries will have stock of fairly mature veggie plants that are either in flower or already fruiting – they will also stock the variety that suits your region (there are quite a few available to the home gardener). They can be planted in the veggie garden or in containers and hanging baskets.
Increase watering as it becomes warmer. Water established vegetables once to twice a week but daily for those in pots.
Spring is the best time to plant strawberries. Read more about growing strawberries here.
Keep harvesting winter veggies.
Feed seedlings with a liquid feed at half strength. Repeat every two weeks.
Fork green manures into the soil and let it stand for three weeks to break down before planting a crop.
Thin out seedlings sown in situ according to instructions on the seed packet.
Use netting to protect seedlings from birds.
Keep frost cloth at hand in case of a late frost.
Leave space in beds for succession planting of green beans, beetroot, carrots and tomatoes.
Give brassicas a boost with a nitrogen-rich fertiliser, and other over-wintering vegetables with a kelp-based liquid fertiliser that acts a tonic, helps to repel aphids, and stimulates soil organisms, leading to increased root development.
Start spraying fruit trees against fruit fly and codling moth once about 75% of the blossoms have dropped off. Spray every 10 – 14 days.
Berries of all kinds are good for your health, and different varieties are readily available. To ensure a good crop prepare beds by working soil over with a fork and adding compost and a balanced fertiliser for fruit and flowers prior to planting.
Earth up early potatoes and prepare trenches for celery, marrows, pumpkins and squashes.
Harden seedlings in seed trays in the sunshine for a few hours a day.
Clean up, position and secure trellises for vertical growing of cucumbers, butternut squashes or runner beans.
Mulch under tomatoes and other bushy vegetables as the soil warms up.
The following herbs can be sown in seed trays for planting out after the last frost: basil, marjoram, oregano, summer savory and thyme.

Projects

Make your indoor plants shine by displaying them on a plant stand. Follow our steps to make this elegant wooden plant stand.

Try something new by making your own herbal soaps. Try out these soap recipes.

Transform a bare wall into a plant feature by making a stunning wall of pots. Find the steps here.

Recipes

Nasturtiums have a peppery taste which makes them perfect for just about anything that needs a spicy kick or a pop of colour. Try these recipes with nasturtiums.

Welcome the spring season by making pasta primavera. Try our recipe here.

< August Gardening Tasks

All Monthly Gardening Tasks