Getting through December to February · Sydney
Summer gardening guide for Sydney
A Sydney summer isn't one thing. Some weeks are dry and 38 degrees with a westerly that strips the moisture out of everything; others are humid, still and punctuated by a downpour that dumps a month of rain in an hour. Gardens have to cope with both, often in the same fortnight, and most summer garden failures come down to treating the two the same way.
The good news: summer is also when a Sydney garden can do the most. Get the watering, the mulch and the timing right and you'll be pulling crops out of it until April.
Maintain your water schedule
When you water matters as much as how much
The same ten minutes of water does completely different jobs depending on when you run it. This is the whole day, ranked.
Avoid wilting plants
Plant SOS: what the symptom is telling you
Almost everything that goes wrong in a Sydney summer looks like "the plant is unhappy". These are the six versions of unhappy, and they need completely different responses. Tap what you're actually seeing.
Tap the symptom — the answer changes
Wilts at midday, recovers overnight
Usually normal — don’t drown it
Plants with big soft leaves close down in the heat of the day to save water, then recover once the sun is off them. If it is upright again by morning, the roots are finding water and the plant is doing exactly what it should. Watering harder in response is the classic summer mistake — you end up with soggy soil, and roots sitting in warm wet ground rot fast.
- Check at 7am, not 2pm
- Mulch, don’t flood
- Shade cloth if it is extreme
Judge every plant by how it looks first thing in the morning.
Improve your gardens soil quality and moisture
Heat takes a real toll on soil. It dries it out, burns off organic matter and leaves sandy ground water-repellent, which is why a bed can look watered on top and be bone dry two centimetres down. Compost and organic matter dug through the beds gives the soil something to hold water with; a good mulch layer stops what you put in from steaming straight back out.
A thin scatter of mulch does close to nothing. Aim for about 75 mm of coarse organic mulch across the beds — enough to shade the soil completely — and keep it pulled back a few centimetres from plant stems and trunks so they don't stay damp and rot. Coarse beats fine in summer: fine mulch mats down and sheds water instead of letting it through.
If water beads on the surface and runs off rather than soaking in, the soil has gone hydrophobic — common in the sandy pockets around the coast and in any pot that has fully dried out. A granular or liquid wetting agent fixes it, and it's worth doing before summer rather than during it.
Don’t overcook your garden
Pots are the first casualties of a Sydney summer. A container in full sun all day gets far hotter than open ground, and the roots against the inside wall cook long before the plant looks stressed. Five to six hours of sun is plenty for almost anything — move pots so they get the morning and are shaded through the worst of the afternoon, group them together so they shelter each other, and remember that a bigger pot holds more water and swings less in temperature. Terracotta looks lovely and dries out fastest of all.
Stop fertilizing in heat waves
A plant in 40-degree heat isn't trying to grow, it's trying to survive. Pushing fertiliser into it forces soft new growth exactly when it can't support it, and concentrated fertiliser salts in dry soil can burn roots outright. Hold off until the heat breaks and the soil is moist, then feed lightly. Seaweed tonic is the exception worth knowing — it isn't a fertiliser, it's a stress tonic, and it genuinely helps plants through and after a hot spell.
When 40 degrees is forecast
The three-day heatwave plan
You usually get a couple of days' warning, and what you do beforehand matters far more than anything you can do on the day itself.
The day before
Load the soil with water
- Deep soak every bed in the early morning — wet soil holds heat far better than dry
- Top mulch up to 75 mm anywhere it has thinned
- Move pots into morning sun and afternoon shade, and group them together
- Rig shade cloth over anything precious or newly planted
- Harvest anything close to ready — it will only cook on the plant
On the day
Don’t make it worse
- Water early, then leave it alone — midday watering mostly evaporates
- No fertiliser, no pruning, no transplanting, no mowing
- A quick soak of pots late afternoon is fine; drenching beds is not
- Ignore midday wilting on established plants — judge them in the morning
- Keep water out for the birds and lizards; they are having a worse day than the garden
Afterwards
Help it recover
- Deep water once the temperature drops, ideally the next morning
- Seaweed tonic to help plants get over the stress
- Wait a week, then trim off what is genuinely dead — not before
- Feed lightly only once the soil is moist and the weather has settled
- Note what struggled: that is your list for what to move or replace in autumn
After a bad day the temptation is to cut all the crispy foliage off immediately. Leave it. Damaged leaves still shade the stems and buds underneath, and plenty of plants shoot again from wood that looks finished. Give it a fortnight, then prune back to where you can see green.
Use the summer months to grow an abundance of vegetables
What to plant, and when in summer to plant it
Sydney's summer is long enough to run two plantings: the heat-lovers that go in early and crop until autumn, and the cool-season crops sown late in summer that carry you through winter. Splitting them like this is the difference between a bumper harvest and a bed of bolted lettuce.
Plant now — heat lovers
- ✓Beans — dwarf and climbing, fast and reliable
- ✓Cucumber, zucchini, squash — watch for mildew
- ✓Sweet corn — plant in a block, not a row, so it pollinates
- ✓Capsicum, chilli, eggplant — they love the heat
- ✓Okra and sweet potato — genuinely thrive in it
- ✓Radish, spring onion, shallots — quick fillers
- ✓Silverbeet — the one leafy green that copes
- ✓Lettuce and chicory — only in afternoon shade, or they bolt
Sow late summer for autumn & winter
- →Broccoli, cauliflower, cabbage — sow Jan–Feb, harvest in the cool
- →Chinese cabbage and kohlrabi — same window
- →Beetroot, carrot, parsnip — sow direct, never transplant
- →Leek and celery — slow growers, start them now
- →Endive — more heat-tolerant than lettuce
- →Potato tubers — late summer planting for an autumn dig
- →Rhubarb crowns — plant once, harvest for years
Pick constantly — beans, cucumbers and zucchini all stop producing the moment they're allowed to mature a fruit, so picking small and often keeps them going for months. And water the soil at the base rather than over the top: wet foliage in a humid Sydney summer is how mildew arrives.
Avoid Mildew by watering early
Powdery mildew is the signature Sydney summer disease, and it shows up as a white dusty film on leaves — cucumber, zucchini, pumpkin, melon and roses are the usual victims. It thrives in humidity, and the single most effective prevention costs nothing: water in the morning, at the base of the plant, so the foliage is dry within the hour. Add airflow to that — space plants properly and thin congested growth — and you'll avoid most of it.
If it does take hold, remove the worst-affected leaves rather than leaving them as a source of spores, and treat early with a milk-and-water spray or a registered fungicide. Once a plant is more white than green, it's usually quicker to pull it out and re-sow.
Pests and diseases in Sydney’s summers
Summer is peak pest season here, and the common ones each have a tell. Aphids cluster on soft new tips and leave leaves sticky. Whitefly lifts off in a cloud when you brush a plant. Spider mite shows as fine stippling and webbing on the undersides in hot dry weather. Caterpillars leave holes and droppings, and cabbage white butterflies will find brassicas within days. Queensland fruit fly is the serious one for anyone growing stone fruit, tomatoes or capsicum.
The approach that actually works is layered rather than heroic: encourage predators by planting flowering herbs and alyssum nearby, hose aphids off with water before reaching for anything else, use exclusion netting on fruit, pick caterpillars off by hand in the evening, and keep plants unstressed — because pests find weak plants first. If you do spray, do it late in the day when bees aren't working, and use the least aggressive product that will do the job.
Keep your lawn long and lush
Summer is the season people scalp their lawns, usually hoping to mow less often, and it's the fastest way to ruin one. Cutting short exposes the soil, which dries out and heats up, and it lets light down to weed seed that a thick lawn would have smothered. Raise the mower instead: buffalo at 40 to 50 mm, kikuyu at 25 to 40, couch at 15 to 30. The extra leaf shades its own roots and holds moisture through the worst of it.
Beyond that, the rules are the same as the rest of the garden. Water deeply once or twice a week rather than lightly every day. Never take more than a third of the leaf blade in one cut. Keep the blades sharp, because a torn tip browns within a day and a whole lawn of them looks scorched. And watch for patches that lift like loose carpet in late summer — that's lawn grub, and it needs treating rather than watering. Our Sydney lawn care checklist has the whole year in order.
Nearly every summer garden disaster in Sydney is a watering-time problem, a mulch-depth problem, or someone fertilising a plant that just wanted to be left alone.
— The Sydney Gardeners crew
Questions
Sydney summer gardening questions
What time of day should I water in summer?
Between 5am and 9am, every time you can. The air is cool and still so almost nothing is lost to evaporation, and the foliage dries within the hour, which stops fungal problems getting started. Late afternoon is an acceptable second choice for pots. Watering after dark is the one to avoid — leaves stay wet all night in Sydney humidity, and that's how mildew and black spot begin.
Should I water every day in a heatwave?
Garden beds, no — one deep soak every second or third day drives roots deeper than a daily sprinkle ever will, and constantly wet warm soil rots roots. Pots are different: a container in full sun can genuinely need water morning and evening in extreme heat, because there's simply no reservoir of soil to draw on.
My plants wilt every afternoon. Are they dying?
Usually not. Big soft-leaved plants close down in the heat of the day to conserve water and recover once the sun is off them. Check them first thing in the morning instead: upright means the roots are finding water and all is well; still limp at 7am means a genuine problem, and it's as likely to be too much water as too little.
Is it true water droplets burn leaves like a magnifying glass?
It's one of the most repeated pieces of garden advice and it's largely a myth — droplets on a flat leaf don't focus enough light to scorch it. The advice to water in the morning is still right, just for different reasons: far less evaporation loss, and foliage that dries quickly rather than staying wet and inviting fungal disease.
Should I fertilise during summer?
Not during a heatwave. Plants in extreme heat are surviving rather than growing, soft new growth can't cope, and fertiliser salts in dry soil can burn roots. Wait for the heat to break and the soil to be moist, then feed lightly. Seaweed tonic is the exception — it's a stress tonic rather than a fertiliser and genuinely helps before and after a hot spell.
How deep should mulch be?
About 75 mm of coarse organic mulch. A thin scatter does almost nothing; at 75 mm the soil is fully shaded, evaporation drops sharply and weed seed can't get the light it needs. Keep it pulled back a few centimetres from stems and trunks so they don't sit damp.
What can I plant in Sydney in summer?
Two groups. Heat lovers going in now: beans, cucumber, zucchini, sweet corn, capsicum, chilli, eggplant, okra, sweet potato, radish, spring onion and silverbeet. And from January, sow the cool-season crops for autumn and winter: broccoli, cauliflower, cabbage, beetroot, carrot, parsnip, leek and celery. Lettuce works in summer only with afternoon shade, or it bolts.
How do I stop powdery mildew on zucchini and cucumbers?
Water in the morning at the base of the plant so leaves aren't wet overnight, space plants for airflow, and thin congested growth. Remove badly affected leaves rather than leaving them to shed spores. Treating early with a milk-and-water spray or a registered fungicide works; once a plant is more white than green, pulling it out and re-sowing is quicker.
Keep reading
Good next steps
Sydney lawn care checklist
The whole year for the lawn, season by season — tick it off as you go.
Mulching
The single best thing you can do for a garden before summer arrives.
Garden maintenance
Scheduled visits so the garden doesn't quietly get away from you in January.
Going away in January?
Don’t come home to a dead garden
Holiday watering, a pre-summer mulch top-up, or regular visits right through the hot months. Free quotes across Sydney, seven days a week.