How to Use a Garden Mulch
Applying a Garden Mulch
The best time and method of applying garden mulches depend on your choice of material and the purpose for which it is mainly required.
Mid spring is generally the best time to apply garden mulches — at this time of year weeds are rarely established and the ground is moist. Don’t mulch any earlier than this, because it is also important for the ground to be warmed up by the sun before mulching. Once applied, a mulch acts as an insulating blanket.
The plants that will benefit most from a regular yearly mulch are the garden’s long-term residents — the shrubs,, fruit trees and bushes, especially the surface-rooting raspberries, and . In all these cases, the plants remain in the same place year after year and there is usually room to work around them. The herbaceous border and also benefit from a spring garden mulch.
As a general rule, leave a gap of 2.5-5cm (1-2in) around plant stems. Most young ornamentals and vegetable plants are liable to suffer if an organic mulch such as compost or manure is in direct contact with them. It may infect them with any disease the mulch contains. Incompletely rotted compost could also burn the stems and basal leaves.
Any plant that is grown as a grafted variety on a rootstock — most roses and fruit trees, for instance — runs an extra risk if any mulch is piled up against its stem. The covering can induce the grafted variety to develop roots of its own from above the union with the rootstock. These roots can change the nature of the plant — on a fruit tree. For instance. The new roots will overpower the dwarfing effect of the rootstock and encourage the tree to grow larger.
Thickness of Garden Mulch
When using bulky organic or inorganic garden mulches around herbaceous plants, roses and other established plants, apply an evenly forked 5-7.5cm (2-3in) deep layer. Smaller plants and young plants require a thinner layer — 2.5cm (lin) is usually adequate.
Straw mulches around raspberry canes, currant bushes and gooseberries are most effective in a layer 7.5-10cm (3-4in) deep.
If possible, mulch all barein your garden, except around annual seedlings or tiny, newly planted rock garden plants until they are well established. But cost — if you have to buy the mulching material — and difficulty of access to the ground around the plants may prevent you from doing this.
If you haven’t got enough mulching material to go round, spread the appropriate depth around each individual plant. Leave the rest of the garden uncovered rather than applying too thin a layer over it.
At the other extreme, don’t be too generous with the mulch. One that is too thick becomes just another rooting zone for weeds and will cut down on the amount of air and water able to get through to the soil and the roots beneath.
Special Garden Mulch Uses
Black or clear polythene sheeting can be used as a surface covering to keep a newly prepared bed in prime condition until sowing or planting — a heavy rainstorm can ruin your hard work. This is useful where you have only a day or two available per week and you are ruled by the weather. Keep the polythene in place with a few bricks or large stones.
A clear polythene mulch can be used to promote the germination of weed seeds in a seed bed. After initial preparations of the bed, anchor the polythene with a few bricks until weed seedlings appear. Then remove it and hoe off the weed seedlings. If you now sow your vegetable or flower seeds without disturbing the surface of the seed bed any further, subsequent weed problems will be reduced significantly.
Straw mulches can be used to protect the crowns of perennial plants which are not reliably frost-hardy. Cover the crowns with straw in late autumn or early winter and anchor it with a sheet of polythene and a few bricks or large stones. Remove the protective garden mulch in mid-spring.
Use clear polythene sheeting as a surface garden mulch to warm up the soil in spring and early summer. Grow early crops — potatoes,, and sweetcorn, for instance — through the polythene and their roots will be kept several degrees warmer than normal, speeding up growth.
Shallow-rooted ground-hugging plants, such as pachysandra and periwinkle, provide a decorative soil cover beneath taller growing plants. At the same time, they form a living, weed-smothering garden mulch for their partners.