What to Plant in August in South Africa

August is a hinge month. On the Highveld it's still winter — frost can catch you right up until the last week or two — but it's also the busiest pruning and planting window of the year, because everything you do now sets up the whole spring and summer season. Miss this window and you're playing catch-up until December.

What you'll learn

• Why August is prime time for pruning and planting deciduous fruit trees
• How to protect stone fruit from peach leaf curl before it starts
• What to sow, plant and feed now versus what to hold for spring
• How to use a polytunnel or greenhouse to get a head start on frost-tender seedlings
• The regional differences that change your August to-do list

The South African context

August sits at the tail end of winter. On the Highveld (Johannesburg, Pretoria, the interior plateau at around 1,500m), frost is still a real risk through most of the month — the last frost typically falls somewhere between mid-August and mid-September, so don't plant out anything frost-tender yet. In the winter-rainfall Western Cape, August is deep winter — cold, wet, and the best month of the year for dormant-season fruit tree work. In summer-rainfall coastal regions (KZN, the Garden Route), frost risk is already low or gone, and spring growth is starting early.

This guide is written from a Johannesburg/Highveld perspective, so adjust timing forward a few weeks if you're on the coast, or hold off a little longer if you're still getting hard frosts.

Fruit trees: this is your window

Deciduous fruit trees are still dormant or just starting to break bud, which makes August the single best month for two jobs that only work while the tree is asleep.

1. Finish dormant pruning now, before bud break. Peaches, plums, nectarines, apples and pears should be pruned while bare, before new growth starts pushing. Once buds swell and leaves emerge, pruning cuts become far more stressful for the tree and you lose the clean view of the branch structure. If you haven't pruned yet, do it this week — waiting into September on early stone fruit varieties means you're pruning into active growth.

2. Spray for peach leaf curl before buds open. Peach leaf curl is one of the most common and frustrating stone fruit problems in SA gardens, and it's almost impossible to treat once leaves have emerged — prevention is everything. Apply a copper-based fungicide or lime sulphur spray while trees are still fully dormant and buds are tight. Spray the whole tree, including the trunk and branch crotches, on a still, dry day, avoid spraying near flowering plants where bees are active, and always follow the label rate. If your peaches or nectarines got leaf curl last spring, this spray is non-negotiable this month.

It's worth knowing that August is also the dormant window in which nurseries sell bare-root deciduous trees — if you're planting new stock this year (bare-root or containerised), getting it in the ground now while it's still dormant gives the roots time to settle before spring growth demands kick in.

Citrus are evergreen and don't follow the same dormant-season rules, but August still matters: hold off on heavy nitrogen feeding until soil starts warming in September, watch for cold damage on exposed branches, and if you see any dieback, wait until after the last frost to prune it out rather than cutting into wood that's still needed for winter protection.

Roses follow the same dormant-pruning logic as deciduous fruit — prune hard now while bare.

Vegetables and the greenhouse: start now, plant out later

The trap in August is planting tender summer crops straight into open beds. Don't — frost can still take out tomatoes, peppers and beans overnight. Instead, use this month to get ahead under cover.

Start seedlings undercover. Tomatoes, peppers, brinjals and cucumbers can all be started from seed now in trays or a seedling tray on a warm windowsill, or directly in a greenhouse bed if it stays reliably frost-free inside. If you're growing in a greenhouse, this is exactly the kind of head start it's built for — seedlings started now will be strong, stocky transplants ready to go into outdoor beds once frost danger passes, typically October on the Highveld.

In-ground greenhouse beds still have room for late brassicas, spinach and lettuce along the cooler, more shaded end, while the sunnier wall can start hosting seed trays for the crops that will eventually move outdoors. If your greenhouse runs east-west with a north wall getting the most sun, that north side is the better spot for anything you want to push along quickly.

Direct sow outdoors (frost permitting, or under cloches): peas, broad beans, spinach and other cool-season greens can still go in. Towards the very end of August, once the worst frost risk has passed in your specific garden, early potatoes can go in — but if you've been caught by late frost before, it's safer to wait until September.

Asparagus crowns, if you're planning a bed, are planted dormant in August — trench them in with plenty of compost, since asparagus is a long-term investment that will occupy the same ground for a decade or more.

Garlic and onions planted in autumn are now bulking up underground. Give them a light top-dress of nitrogen-rich fertiliser (LAN or a balanced 3:1:5) this month to support the leaf growth that feeds bulb development — but ease off nitrogen again once bulbing really kicks in during spring, since too much late nitrogen delays maturity.

Soil, compost and beds

August is a good, quiet month to get soil ready before the spring planting rush. Dig kraal manure or finished compost into any beds that will take summer crops, so it has time to break down further before planting. Turn compost heaps that have slowed down over winter — cold weather stalls decomposition, and a turn now with a nitrogen boost (grass clippings, kitchen scraps) will get it active again in time for spring additions. If you're converting lawn to new growing beds, August's cooler, drier soil is easier to dig and clear than waterlogged spring ground.

Common mistakes

• Planting frost-tender seedlings outdoors too early because a warm afternoon feels like spring — one late frost undoes weeks of growth.
• Skipping the peach leaf curl spray because the tree "looks fine" — by the time curled leaves appear, it's too late to treat that season.
• Pruning stone fruit after buds have swollen, which stresses the tree and can reduce fruit set.
• Over-feeding citrus with nitrogen in August — wait until the soil warms up, or you push soft new growth straight into a possible late frost.
• Leaving newly planted trees out of the ground or unwatered for too long after planting — roots dry out fast and establishment suffers.
• Forgetting to top-dress overwintering garlic and onions, leaving them short on nitrogen right when they need it for bulb development.

What to do this week

• Finish any outstanding dormant pruning on peaches, plums, nectarines, apples, pears and roses before buds swell further.
• Apply a copper or lime sulphur spray to stone fruit for peach leaf curl prevention, on a still, dry day.
• If you're planting new fruit trees or roses this year, get them into the ground now while still dormant.
• Start tomato, pepper, brinjal and cucumber seed in trays under cover, ready for an October transplant.
• Top-dress overwintering garlic and onion beds with a nitrogen fertiliser.
• Turn slow compost heaps and add a nitrogen boost to reactivate them.
• Dig kraal manure or compost into beds earmarked for spring/summer planting.
• Hold off planting anything frost-tender directly outdoors until your local last-frost date has safely passed.

FAQ

Is it too late to prune my fruit trees in August?

Not yet, but move quickly. As long as buds haven't swollen and burst, you're still in the dormant window. Early stone fruit varieties break bud earliest, so prioritise peaches and nectarines first if you're behind.

Can I plant tomatoes outside now if I cover them at night?

It's risky on the Highveld. A single hard, unprotected frost can still occur into September, and covering doesn't always save a young seedling in an open bed. Starting seed undercover now and transplanting after the last frost date is safer.

Why does my peach tree get curled, blistered leaves every spring?

That's peach leaf curl, a fungal disease that infects new leaf tissue as it emerges from the bud. The spray window is now, before buds open — once leaves show symptoms, the infection for that season is already established and spraying won't reverse it.

Do I need to feed my citrus trees in August?

Hold off on nitrogen-heavy feeds until soil temperatures start rising in September. Feeding too early can trigger soft new growth vulnerable to a late frost.

What can I still direct-sow in August?

Peas, broad beans, spinach and other hardy greens are fine. Potatoes can go in towards the very end of the month once frost risk has clearly passed in your area, but many gardeners prefer to wait for September to be safe.

Summary

August rewards the gardener who moves before spring rather than reacting to it. Finish dormant pruning and the peach leaf curl spray this week, get any new trees or roses into the ground while they're still dormant, and use a greenhouse or sunny windowsill to start summer vegetable seedlings well ahead of the last frost. Keep frost-tender crops undercover until your local frost date has genuinely passed, and use this quieter month to get soil and compost ready for the planting rush that's about to start. Do the groundwork now, and September and October become about planting out strong, established seedlings rather than starting from scratch.