Mulches are loose coverings or sheets of material placed on the surface of cultivated soil. Mulches can be applied to bare soil or to cover the surface of compost in containers.
Depending on the type of mulch used, there are many benefits of mulching including:
- Help soils retain moisture in summer
- Suppress weeds
- Improve soil texture
- Deter some pests
- Protect plant roots from extreme temperatures
- Encourage beneficial soil organisms
- Provide a barrier for edible crops coming into contact with soil
- Give a decorative finish
Mulches can be split into two main groups; biodegradable and non-biodegradable.
These break down gradually to release nutrients into the soil and help improve its structure. Layers will need replacing when the material has fully rotted down. Among the best materials are leaf mould, garden compost, spent mushroom compost, wood chippings, processed conifer bark, well rotted manure, straw (for strawberries), spent hops (poisonous if eaten by dogs) and seaweed.
Non-biodegradable mulches do not boost the fertility or structure of the soil, but they do suppress weeds, conserve moisture and some have the added advantage of looking decorative. Slate, shingle, pebbles, gravel, stone chippings and other decorative aggregates are often used as a mulch across beds. Crushed CDs, sea shells, tumbled glass and similar materials can be used on the surface of containers.
Sheet mulches or woven landscape fabric are ideal for new beds or borders. After laying, slits can be made in the fabric, allowing direct planting through it. The downside is these mulches do not look very attractive, but they can be camouflaged with gravel, bark or others materials. To allow rain and irrigation water to reach the roots it’s best to choose a permeable sheet.