Hot conditions are brutal to a garden and lead to many vegetable-garden failures, so let mulch work its summer magic writes Maureen Gilmer, AAP

Mulch could save the day or your garden this hot season if you let it work its summer magic. When it seems so hot that you could probably fry an egg on the footpath, you can almost believe that you could fry another one on exposed garden soil, too.

At any rate, that soil can get hot in summer. And then we ask young, tender plants to grow in such soil – material that heats up under the super-dry surface. No wonder our vegetable gardens fail. But you can mulch at home and help save your garden.

Shade always helps, of course. But many plants need full sun to grow, so you can’t put up an umbrella. The only bit that needs total shade is the roots.

The traditional solution is to spread straw over the ground as a mulch around each plant to create an insulating layer that protects the soil from direct solar exposure.

The word “mulch” describes a specific type of material that is non-specific in its origins but functions much like goose down in a winter coat. Down retains its loft to create a thick zone of dead air for maximum insulation. In the garden, people have long used mulch around their vegetables to create a similar insulation layer between the sun and soil to keep conditions underground cooler.

Mulch does other things, provided it’s five or six centimetres deep and preferably more.

  • First, mulch prevents surface crusting of the soil so water introduced goes straight in.
  • Second, it shades the soil so roots will find a sizeable zone of cool rich soil.
  • Third, mulch laid thick enough cuts off light to the soil surface, denying weeds incentive to grow. You can also use mulch in pathways through the veggie garden to keep your feet clean while watering or picking.

Mulch is not a soil amendment because the best materials resist decomposition. If they are tilled in, you risk nutritional problems in the soil because the lignin in these cell walls is hard for microbes to break down. They may even rob the soil of its nitrogen to help in the decomposition process.

You can re-use mulch season after season. In late autumn, rake mulch off your garden and into a pile for reuse. It’s great for freeze/thaw mulching after the first frost, or just stockpile for the following year’s food garden.

Straw and sugar-cane mulch is commonly used because it’s widely available and cheap. A single bale of straw can cover even a good-sized garden with plenty of insulation for plants and pathways. Even if there’s a lot of rain and mud, the straw holds its loft because it doesn’t get soft.

Look for mulches you can obtain for little or no money, such as wood chips, bark chips or sawdust from a local timber mill or autumn leaves that you’ve put aside to use for the following summer’s garden mulch.

Mulches aren’t laid out until the soil becomes warm enough and plants are under way. If you put it on too early, the soil won’t heat up enough properly to germinate your seeds or stimulate seedling growth.

Keep your mulch layer 3cm or more away from the base of the plant to avoid stem problems.

Mulches aren’t always the best-looking part of the food garden, but they are among the most essential to enhancing plant health. Nothing works better for water conservation, and they also help eliminate or limit weeds.

The best news? A well-mulched garden means you’ll have more time to go to the beach or on a picnic – rather than staying home to weed. Plus check out our watering tips.