Watering a veggie patch through an Adelaide summer

Adelaide summers are long, hot and dry, and a run of days over 35° can undo weeks of work in an afternoon. The good news is that a few habits matter far more than how much water you use.

Water deeply, not daily

A quick sprinkle every evening wets the top few centimetres and teaches roots to stay near the surface, where the soil dries out first. A deep soak every two to four days pushes water down to where roots can follow it.

• Aim to wet the soil to about the depth of a trowel blade (15 to 20 cm).
• Check with your finger or a trowel an hour after watering. If it's dry below the top few centimetres, water for longer next time.
• Sandy soils need water more often; clay holds it longer but needs a slow trickle so it soaks in rather than running off.

Water early

Morning is best. The plant starts the hot part of the day fully watered, less is lost to evaporation, and leaves dry quickly, which helps keep fungal problems like powdery mildew down. If you can only water in the evening, water the soil, not the leaves.

On a forecast heatwave day, water deeply the morning before and the morning of. Patchmates sends a heat alert ahead of hot days so you've got time to get ready.

Mulch is half the job

A 5 to 7 cm layer of mulch keeps the soil cooler and slows evaporation. Pea straw, lucerne and sugar cane mulch all work well in veggie beds. Keep it a hand's width away from stems, and top it up as it breaks down.

Water the roots, not the paths

Drip line or a soaker hose under the mulch puts water where it's needed and wastes very little. If you hand water, use a gentle shower at the base of each plant and give big feeders like tomatoes, zucchini and corn the most.

Signs you've got it wrong

• Wilting in the afternoon, recovering by evening: often normal on hot days. Check the soil before adding water.
• Wilting in the morning: the plant is short of water. Water deeply now.
• Blossom end rot on tomatoes (a dark, sunken patch on the bottom of the fruit): usually uneven watering. Keep the soil evenly moist.
• Yellowing lower leaves and soggy soil: too much water, or poor drainage.

Shade on the worst days

Leafy greens and young seedlings appreciate a little shade cloth (30 to 50 percent) on the hottest afternoons. Even an old sheet on stakes helps for a day or two.

Use what you've got

Check your council and SA Water's current water-use rules before setting up irrigation, and talk to your council about any rainwater tank or greywater set-up for edible gardens.