Choosing the Right Mulch for Your Garden Beds
Mulch is a layer of material spread over the soil surface, and it is one of the most useful things you can add to a garden. It keeps the soil moist, reduces weeds, moderates soil temperature, and as organic types break down, they feed the soil.
Types of mulch
- Wood chips and bark. Long-lasting and good for trees, shrubs, and paths.
- Straw. Light and cheap, popular in vegetable beds. Use weed-free straw.
- Leaf mould or shredded leaves. Free and excellent for soil.
- Compost. Feeds plants but breaks down quickly, so it is often used under another mulch.
- Gravel and stone. Last a long time and suit dry-climate gardens, but add no nutrients.
How much to apply
A layer of about five to eight centimetres (two to three inches) is a good guide for most organic mulches. Too thin a layer lets weeds through, and too thick a layer can keep water from reaching the soil.
Keep it away from stems and trunks
Do not pile mulch against the trunk of a tree or the stems of plants. This so-called volcano mulching holds moisture against the bark and can encourage rot and pests. Leave a small gap, about the width of your hand, around the base.
When to mulch
Apply mulch on moist soil, once the ground has warmed in spring or after planting. In regions with hot summers, it helps to keep roots cool. In cold areas, a layer after the ground begins to freeze can protect roots.
A few cautions
- Avoid using fresh sawdust or large amounts of fresh wood chips mixed into the soil, which can temporarily tie up nitrogen.
- Pull weeds before mulching, as mulch will not smother established perennials.
- Check where the material comes from and avoid anything treated with chemicals.
Topping up the mulch each year keeps beds tidy, healthy, and easier to look after.