Nurturing your soil year-round: an Adelaide seasonal plan

Healthy soil doesn't happen in one weekend. It builds up a little at a time, season after season. Adelaide has a Mediterranean-style climate, with cool wet winters and long hot dry summers, so the jobs that help your soil change through the year. Here is a simple plan.

Autumn (March to May): build and protect

Autumn is the best time of year to work on your soil. The heat has eased, the first rains are on the way, and soil life wakes up as the ground cools and moistens.

• Spread compost. Add a few centimetres of compost or aged manure over beds that are about to be planted, and around fruit trees and shrubs.
• Sow a green manure. In beds you won't use over winter, sow a cool-season mix such as broad beans, field peas, oats or ryegrass. Slash it in spring before it sets seed and let it break down on or just under the surface for a few weeks before planting.
• Mulch before the rain. Top up mulch so it's in place when the rains come. It stops heavy rain crusting bare soil, and it protects the soil life you've just fed.
• Plant for winter. Garlic, brassicas, broad beans, peas and leafy greens go in now, so keep roots growing in your beds.
• Fix water repellence. If water beads on dry sandy soil instead of soaking in, treat it now, before the winter rain (see below).

Winter (June to August): go gently

Winter is wet and cool, so soil life slows down. The main job is to avoid doing damage.

• Don't work wet clay. Digging or walking on wet clay squashes out the air and leaves hard clods that last for months. Wait until a handful crumbles when you squeeze it, rather than smearing or forming a sticky ball.
• Keep off the beds. Use paths or boards to spread your weight if you must step in.
• Watch drainage. Note any spots where water sits for days. They may need raised beds, more organic matter or, for heavy clay, gypsum, which can help some clay soils drain better.
• Keep roots growing. Green manures and winter crops keep feeding the soil life through the cold months.
• Make compost. Collect autumn leaves and prunings now. You'll want plenty of compost in spring.

Spring (September to November): feed and plant

Spring is when most summer crops go in, so it's time to load up the beds.

• Top up compost before planting. Spread a fresh layer of compost on beds before you plant tomatoes, zucchini, capsicum, cucumbers and other summer crops.
• Turn in green manure. Cut green manure crops down when they start to flower. Chop them and leave them on the surface or lightly fork them in, then wait a few weeks before planting into that bed.
• Check pH if plants struggle. A simple home test kit will tell you whether your soil is very acid or very alkaline. Many Adelaide soils lean alkaline, and most veggies prefer slightly acid to neutral soil.
• Mulch by late spring. Get mulch down before the first heatwave. Water the bed well first, then mulch.

Summer (December to February): shade and water

Adelaide summers are hard on soil. Bare ground can get very hot in full sun, enough to cook the soil life near the surface.

• Mulch thickly. Keep 5 to 7 cm of straw-type mulch in veggie beds and 7 to 10 cm of wood chips around trees and shrubs. Top it up as it breaks down.
• Water deeply, less often. A long soak that wets the soil well down encourages deep roots. Light daily sprinkles only wet the top layer and mulch.
• Water early. Morning watering means less is lost to evaporation and leaves dry off before night.
• Use shade. Shade cloth over veggie beds during heatwaves protects plants and keeps the soil cooler.
• Don't leave beds bare. If a bed is empty, mulch it or cover it until autumn planting.

Water-repellent sandy soils

Sandy soils in Adelaide's coastal and northern suburbs, and potting mixes left to dry out, can become water repellent. A waxy coating builds up on the sand grains, and water runs off or straight past the roots instead of soaking in. You'll often see dry patches even after rain or watering.

To fix it:

• Use a soil wetting agent. These help water spread through repellent soil. Liquid and granular forms are both available. Apply as the label directs, usually in autumn before the rain and again in spring before summer, and water it in well.
• Add organic matter. Compost improves how sandy soil holds water over time.
• Keep it mulched and moist. Repellence is worst when soil dries out completely.
• Make water slow down. Shallow basins around plants and drip irrigation help water soak in rather than run off.

Signs of healthy soil

Check your soil a couple of times a year. Healthy soil usually shows:

• Plenty of earthworms.
• A dark colour and a crumbly texture that holds together loosely.
• A sweet, earthy smell, not sour or rotten.
• Water that soaks in quickly and doesn't pool.
• Roots that spread easily rather than turning sideways at a hard layer.
• Mulch and compost that break down over a season.

If your soil is pale, hard, smelly or full of puddles, more organic matter and mulch, and less traffic, will usually make a real difference within a year or two.

A quick seasonal checklist

Patchmates works out the seasons for your suburb, so planting reminders and soil jobs line up with your local weather.