In ecological horticulture, mulch refers to organic matter – such as leaves or grass cuttings – that is applied to the soil to protect it and supply it with nutrients. Mulching is the process of doing so by adding a loose layer of shredded plant material on top of the soil. Mulching is a valuable method to use in almost every area of your garden, and for home gardeners it’s also a great way to save time, money and effort.
How does mulching work?
Mulching helps soil retain moisture by shading the earth and acting as a blanket. It means water can be stored more effectively in the ground, so the soil remains loose and will not dry out too quickly. Mulching also helps plants to grow by forming a protective layer against heavy rain and cold temperatures. Over time, plant matter used for mulching is broken down by earthworms and soil-dwelling organisms into valuable natural fertilisers and nutrients for plants.
Mulching material
A huge range of natural substances is suitable to use as mulching material, from chipped bark to sawdust – and you might not even need to go to your local garden centre. You may find that your usual garden waste offers everything you need to start mulching yourself. Take a look at our suggested materials and uses.
Shredded wood matter
Suitable for use under rooted hedges and trees.
Ideal as a path covering.
Can accelerate plant growth due to the high nitrogen content released during degradation.
Grass cuttings
Can be used in all areas.
Use a layer approximately 2 to 3 cm thick on flowerbeds and plants.
Don’t apply as a thicker layer because cuttings can clump together and smother the soil.
Never use diseased grass or grass cuttings that include seeds.
Leaves
Leaves from birch, maple, beech and all fruit trees can be used freely.
Leaves from nut, chestnut and oak trees should be used in small quantities and must be mixed with other leaves for mulching.
This is because they are high in tannic acid, which is very hard to degrade and has a negative impact on the nutritional balance in the soil.
Chipped bark
Suppresses thistles and other weeds.
Only suitable for paths and under flowers, fruit trees and bushes, as it can lead to high levels of tannic acid in the soil.
Not suitable for vegetables and shrubs.
You should use a layer at least 10 cm thick to benefit from its full effectiveness.
Gravel, chippings and stones
Inexpensive.
For use around perennial herbs and shrubs.
Recommendation: use light-coloured variants in sunny spots as they will not heat up as quickly. Dark variants store heat for longer.
Water-permeable and breathable.
Not suitable for dense soil due to its weight.