How to Protect Plants From Heat in Australia: 7 Tips

Quick takeaway: how to protect plants from heat

If you only do five things before the next hot spell:

• Spread a thick layer of mulch over bare soil to keep roots cooler and slow evaporation
• Water deeply in the early morning rather than lightly every day
• Shade seedlings, leafy greens and pots through the hottest part of the afternoon
• Move pots and hanging baskets out of full western sun
• Treat dry or water repellent areas with Searles Penetraide, a re-wetting agent, and water it in before mulching so the soil can absorb moisture for the next 12 months

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Why are my plants wilting in the heat?

Wilting in the middle of a hot day is not always a sign that your plant is dry. Plants lose water through their leaves faster than their roots can replace it, so they droop to reduce the surface area exposed to the sun. Many plants recover on their own once the temperature drops in the evening.

The wilting to worry about is the kind that is still there first thing in the morning. That usually means the soil is genuinely dry, the roots have been damaged, or the soil has gone water repellent and the water is running straight off instead of soaking in.

Before you reach for the hose, push a finger into the soil to about knuckle depth. If it is damp underneath, your plant is coping with the heat rather than crying out for another drink.

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What heat stress looks like in plants

Heat stress shows up in a few familiar ways:

• Wilting or curled, rolled leaves through the afternoon
• Crispy brown edges or scorched patches on leaves, especially on the sun facing side
• Flowers and small fruit dropping before they develop, which is common in tomatoes, capsicum and beans in extreme heat
• Pale, bleached patches on leaves and fruit where the sun has burnt the tissue
• Growth slowing right down, even though you are watering and feeding

None of this means you have failed as a gardener. Gardening does not need to be perfect, and a tough summer is something every Australian garden goes through.

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How to mulch garden beds before the heat hits

Mulch is the single easiest win for a hot summer. A layer of organic mulch shades the soil, keeps root zones cooler, slows evaporation and helps suppress weeds that compete for moisture.

A few tips for mulching well:

• Apply Searles Penetraide and water the soil well first, then mulch. Mulching over dry soil locks the dryness in
• Aim for a layer around 50 to 75 mm thick over garden beds, a little thinner in pots
• Keep mulch pulled back a few centimetres from trunks and stems so they do not stay wet and soft
• Top up through summer as the mulch breaks down and settles

Searles Sugar Cane Mulch is an easy choice for veggie patches and garden beds, and it breaks down over time to add organic matter back into the soil. For pots, a sprinkle of mulch or a layer of pebbles over the mix helps slow moisture loss on hot days.

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Watering habits that help plants cope with hot spells

More water is not always the answer. Better watering is.

Water early in the morning so plants start the day fully charged and foliage dries quickly. Evening watering is the next best option if mornings are not possible, though wet leaves overnight can encourage fungal problems.

Water deeply and less often. A long, slow soak encourages roots to grow further down where the soil stays cooler and damper, while a quick daily splash keeps roots near the hot surface. Direct water at the base of the plant rather than over the leaves.

If water beads up and runs off, your soil may be water repellent. Give it a slow trickle, water in stages, or apply a wetting agent such as Searles Penetraide Re-Wetting Granules to help moisture soak through again. Starting with a quality growing medium makes a big difference too, and our guide to potting mixes and soils walks you through choosing the right one.

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How to use shade and timing to protect plants from heat

Some plants simply need a break from the sun. Leafy greens, seedlings, ferns and berries all appreciate protection through the hottest hours.

Try these:

• Rig up shade cloth, an old sheet or a beach umbrella over vulnerable beds on forecast scorchers
• Group pots together in a shadier spot so they shelter each other and create a more humid pocket
• Move hanging baskets and small pots off hot paving and brick walls, which radiate heat long after sunset
• Hold off on planting new seedlings until a cooler stretch of weather is forecast

Avoid heavy pruning and strong fertilising right before a heatwave. Both push out soft new growth that scorches easily. Wait until the weather settles, then feed to help plants recover with something like 5 IN 1 Organic Fertiliser or a liquid feed. Searles Seamax, a seaweed-based organic fertiliser, is also worth adding to your summer routine, as it helps decrease plant stress and increase resistance to drought.

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How to protect plants from heat in Australia: pots, seedlings and lawns

Pots dry out fastest because they heat up from all sides. Check them daily in summer, use larger pots where you can, and move them to a shadier position through the worst of it. Avoid leaving saucers full of water, as this can lead to fungal rot and pest issues. A quality potting mix that holds moisture well gives container plants a much better chance.

Seedlings have small root systems and few reserves, so shade them, keep the surface evenly damp and plant them out late in the day.

For lawns, mow a little higher through summer. Longer blades shade the soil and the roots beneath. Water deeply once or twice a week rather than every day, and expect some browning in extreme heat that greens up again with rain.

Searles products are made in Australia and developed for Australian gardening conditions, so they are built for exactly these kinds of summers.

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FAQs

Why are my plants wilting even though I water them every day?

Afternoon wilting is often a normal response to heat rather than a lack of water, and plants usually perk up by evening. Daily light watering can also keep roots near the hot soil surface, so water deeply and less often instead, and check the soil with your finger before you water again.

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What is the best mulch for hot weather in Australia?

An organic mulch such as sugar cane mulch, bark or pea straw works well because it shades the soil, slows evaporation and breaks down to improve the soil over time. Searles Sugar Cane Mulch is a popular option for veggie patches and garden beds.

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How thick should mulch be to protect plants from heat?

Around 50 to 75 mm over garden beds is a good guide, with a slightly thinner layer in pots. Water the soil first, then keep the mulch pulled back a few centimetres from trunks and stems.

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Should I water my garden in the morning or the evening in summer?

Early morning is best, because plants start the day with full moisture and the foliage dries quickly. Evening watering is the next best option, though wet leaves overnight can encourage fungal problems.

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Can plants recover from heat stress?

Many can, especially if the roots are still healthy. Water deeply, add shade, hold off on heavy pruning and fertilising until the weather cools, then feed to support new growth.

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Ready to heat proof your patch? Grab your mulch before the next hot spell and ask for Searles at your local garden centre. Find a Searles stockist near you.

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