Mulch

Mulching simply means covering bare soil with a layer of material instead of leaving it exposed. It is one of the highest-value, lowest-effort jobs in the garden, and it does the work of several chores at once: holding in moisture, smothering weeds, feeding the soil and shielding roots from frost.

What to use

Different materials suit different jobs, and most are free or cheap:

• Garden compost or well-rotted manure — the best all-rounders. They feed the soil as well as covering it, so they suit vegetable beds.
• Leaf mould — rotted-down autumn leaves; gentle, crumbly and good for improving soil structure.
• Bark or wood chip — long-lasting and tidy, ideal around shrubs, paths and perennial borders.
• Straw — keeps strawberries and squash clean and off damp soil.
• Grass clippings — useful in thin layers, but pile them too thick and they turn slimy and smelly, so add little and often.

Why it works

A good mulch earns its keep in four ways. It retains moisture by slowing evaporation, which means far less watering through a dry British summer. It suppresses weeds by blocking the light their seedlings need. It feeds soil life as it slowly breaks down, encouraging the worms and microbes that build a fine tilth. And a thicker winter layer gives roots some frost protection, while sheltering the surface from heavy rain that would otherwise wash nutrients away.

This is exactly why mulching sits at the heart of no-dig gardening: rather than turning the soil over, you feed it from the top and let the worms do the digging for you.

How and when to mulch in the UK

Aim for a layer around 5cm deep. The two key windows are autumn, once beds are cleared, to protect soil over winter, and spring, after the ground has warmed but before summer dries it out.

The golden rule is to mulch onto moist soil. Mulch holds in whatever moisture is already there, so spreading it over bone-dry ground simply keeps the soil dry. Water first if you need to, or wait for a wet spell.

One thing to avoid: never pile mulch up against plant stems or tree trunks. Trapped moisture against the bark or stem can cause rot and invites slugs. Leave a small gap — about a finger's width — around each plant, and top the layer up once or twice a year as it breaks down.