Part of the Gardening Owl Maintenance collection. Practical, season-aware advice for caring for your garden.
What is mulch?
A mulch is a layer of material laid over the soil surface. Organic materials, such as composted bark, leaf mould and well-rotted compost, help reduce evaporation and suppress germinating weeds. Many gradually improve soil structure as they decompose. Inorganic materials, such as gravel, are used for some dry or decorative plantings but do not feed the soil.
Choose mulch for the job
- Composted bark: useful around established shrubs and ornamental borders, especially where a longer-lasting surface is wanted.
- Well-rotted compost: suits many vegetable beds and borders; avoid fresh, uncomposted kitchen material as a surface dressing.
- Leaf mould: a valuable soil conditioner and surface mulch for many beds.
- Straw: can help keep fruit off damp soil in suitable crops; check it is free of unwanted seeds.
- Gravel: suited to some drought-tolerant planting; choose it for the plants and soil conditions rather than as a universal solution.
When to mulch
Mulching is useful after weeds have been removed and the soil is moist but not waterlogged. Spring is a common time as soil starts warming, while autumn can be useful for protecting exposed soil. Applying a very thick cold layer too early may slow spring warming in some situations.
How to apply mulch
- Remove established weeds first and water dry soil if needed.
- Spread most organic mulches in an even layer of roughly 5cm, adjusting to the material and plants.
- Keep the mulch a little clear of plant stems, crowns and tree trunks to reduce rot risk.
- Avoid burying low-growing plants or trapping mulch against wooden structures.
- Top up gradually as organic layers break down.
Common mulching mistakes
Do not pile mulch into a cone around tree trunks. Avoid laying thick material over waterlogged soil, burying tender seedlings or assuming mulch removes the need to water newly planted crops. Check whether slugs shelter underneath in damp conditions.
Mulching and soil health
Mulching helps protect soil from heavy rainfall and sun. It works best alongside sensible watering, good drainage and improving soil structure with appropriate organic matter. See Common Garden Soil Problems for deeper troubleshooting.
Related gardening guides
Garden watering · Natural weed control · Best compost for vegetables · Maintenance overview