Mulches and mulching

Steve and Val Bradley look at the range of organic and non-organic mulches available and explain how to use them to suppress weeds, warm up soil and conserve moisture

- Steve and Val Bradley

Wood chippings, and other organic mulches, decompose over time and will eventually need topping up

MULCHES are loose coverings (or sheets of material) placed on the surface of bare soil or the surface of compost in containers. They can be a useful alternative method of weed control rather than using weed killers. They work because they block out daylight, which stimulates weed seeds to germinate. The seeds are still there, but they remain dormant.

A straw mulch is ideal for weed controlling and water retention

Organic mulches like rotted leafmould release small amounts of nutrients

Helping moisture retention

A good mulch will also help with moisture retention in the soil or compost, by reducing surface evaporation, and dark-coloured fabric mulches can be used to warm up a seed bed or planting area in spring by absorbing the sun’s heat and transferring it to the soil beneath, making it warmer than the surrounding soil. Light-coloured mulches are used in greenhouses and cold frames to control weeds and reflect light, helping to improve light levels around young plants during the winter months.

Mulches can be divided into two main groups: organic and non-organic. The two are used together where an organic layer, such as shredded bark, is used to cover a non-organic fabric cover.

Organic mulches