Mulching — Covering the Soil to Save Water and Feed It

Mulch is simply a layer of material spread over the soil surface around your plants. That one layer quietly does four jobs at once: it keeps the soil moist, blocks weeds, steadies the soil temperature, and — if it's organic — rots down to feed the soil. Bare soil is the exception in nature; mulch copies the leaf-litter that covers healthy ground.

Use an organic mulch — straw, compost, shredded leaves, grass clippings, wood chips — which breaks down and feeds the soil. Straw is great around vegetables; compost doubles as a feed; wood chips suit paths and shrubs. (Stone or plastic mulches conserve water and block weeds too, but never feed the soil.)

Mulch locks in whatever it covers, so clear the weeds and water the ground well BEFORE you spread it. Mulching over dry soil keeps it dry; mulching over weeds just protects them. Warm, moist, weeded soil is what you want to seal in.

Lay the mulch several centimetres thick — thick enough that no light reaches the soil, or weed seeds will sprout straight through it. Top it up through the season as an organic mulch rots down and thins.

Pull the mulch back a little from the base of each plant and away from tree trunks. Mulch piled against a stem holds damp right where the plant is most vulnerable and causes rot and pests — leave a small clear collar around every stem.

A thin surface layer punches far above its weight because it works on the boundary where soil meets air. MOISTURE: most water leaves a garden by evaporating straight off bare soil, and mulch simply caps that — it shades the surface and traps humid air beneath, so far more of your watering and rain stays in the root zone, cutting watering dramatically. WEEDS: nearly all weed seeds need light to germinate, so a mulch thick enough to keep the soil dark starves them out before they start. TEMPERATURE: the same insulating blanket buffers extremes — keeping roots cooler in summer heat and, laid thick in autumn, protecting them from hard frost, which is exactly how you overwinter root crops in the ground. And with an ORGANIC mulch there's a fourth, slower gift: as straw, leaves and compost rot on the surface, earthworms and soil life drag them down and turn them into humus, steadily building the soil's fertility and crumb structure from the top, the way a forest floor feeds itself — a living mulch, not just a cover. Two cautions complete the picture. Keep coarse, woody, high-carbon mulches ON TOP and never dug in, because the microbes that decompose fresh wood or straw temporarily borrow nitrogen from the soil to do it, briefly starving your plants if it's mixed in (on the surface it's harmless). And keep mulch off stems and trunks, since trapped damp there invites rot. Mulching is as old as farming, and it remains the single easiest thing a grower can do to save water, beat weeds and build soil all at once.