Autumn Leaves in the Garden: Why Not to Rake Up All of Them
Gardening advice for autumn: fallen leaves improve soil and protect it in winter, so in many spots they are best left in place. Leaves should still be cleared from lawns, paths and terraces, and diseased leaves should not stay in beds or compost.
Carefully raking up and removing every fallen leaf in autumn deprives garden soil of a valuable natural resource, according to an article based on foreign press material. Leaves gradually decompose, and soil organisms turn them into a substance that helps the soil retain moisture and become looser. For this reason, in many parts of the garden it is better to leave leaves where they fall rather than take them to an organic waste bin.
What leaves give the soil
Fungi, bacteria, woodlice and earthworms feed on fallen leaves. As the leaves break down, they form a material that improves soil structure. In sandy soil it helps retain water and nutrients, while heavy soil becomes looser and more permeable to air. In winter a layer of leaves also protects the soil from drying out and from sharp temperature swings.
Leaves should not be treated as the main fertiliser, however. Before the leaves fall, trees move much of their nutrients back into the trunk and roots, so leaves cannot fix an acute nutrient shortage in the soil.
Decomposition speed varies
How fast leaves break down depends on the tree species. Leaves of linden, hazel, maple, hornbeam, elder and fruit trees decompose faster and suit mulching around perennials, under shrubs and trees, and in vegetable beds. Oak, walnut and chestnut leaves break down more slowly; they are better left under hedges and shrubs or used in compost. The soil should not be covered with too thick a layer, because compacted wet leaves can leave the soil short of air.
Where leaves should still be removed
Leaves should be cleared regularly from lawns, as they block light and air, and the moisture beneath them encourages diseases such as snow mould. They should also be removed from paths and terraces, where they become slippery when wet and can cause falls. Other healthy leaves can be composted or piled in a sheltered heap with twigs and brushwood, which can become a refuge for hedgehogs, insects and other small garden dwellers.
Diseased leaves should not be left in beds or added to compost, since disease agents and pests can overwinter in them. Depending on the disease and local municipal rules, they should go into household waste or an organic waste bin.
