How to Compost – Making Leafmould
Autumn leaves are one of the best sources of-improving organic matter. They take a year or two to decay into a dark, crumbly material known as leafmould. Newly fallen autumn leaves could be used directly on the garden, but converting them to leafmould makes them easier to handle and less likely to blow away if applied as a surface mulch. The advantage of leaves is that they are free, easy to obtain and clean to handle.
Fallen leaves from any trees and shrubs, other than conifers and other evergreens, will make leafmould. Different species decay at different rates, but all will turn to leafmould eventually.
Diseased leaves which can pass on infection, such as those with rose blackspot or apple scab, are best avoided. Alternatively, use them to make a batch of leafmould which is used around unrelated plants.
Collecting the leaves
The best time to collect autumn leaves is when they are wet after rain. This saves watering them later. A quick method for collecting leaves on a lawn is to run the mower over them with the grass box on. This chops the leaves and adds some grass mowings, which will speed decay. Machines designed specifically to collect leaves are also available.
Sources of leaves
Leaves can be collected from parks and cemeteries (with permission) and from quiet streets. Leaves from busy roadsides are best avoided as they can be contaminated with lead and other pollutants. Some councils may deliver if you can cope with a lorry load. Ask for those from parks, not from the roads.
The decay of autumn leaves is a slow, cool process carried out by fungi — very different from the composting process. To make leaf-mould, simply collect leaves together where they will not blow away, watering them well if they are dry.
The leaves may be piled up in a sheltered corner. Alternatively, use a simple container made by fixing wire mesh netting around four corner posts. Smaller quantities of leaves can be stuffed into black plastic sacks which are then tied loosely at the top.
Leafmould contains little in the way of plant foods but is an excellent soil conditioner. As soon as the leaves have started to break up and darken in colour, they can be used as a mulch or dug into the soil. This may be as soon as the following spring, but the process can take much longer depending on the type of leaves used and on how moist they are. A finer grade of leafmould, suitable for potting mixes, will take 2-3 years to achieve.
The ingredients required are equal quantities by volume of fine 2-3 year old leafmould and chopped comfrey leaves.
Fill a dustbin or plastic sack with alternate 7.5-10cm (3-4in) layers of leafmould and chopped comfrey. Leave for 2-5 months (depending on the time of year), checking on the moisture levels occasionally. If the mixture turns soggy, or if it is so dry that little has changed, empty out the container. Leave the contents to dry, or add water as appropriate, before refilling the dustbin or sack.
The comfrey leafmould is ready to use when the comfrey leaves have virtually disappeared.
Making Comfrey Leafmould
Fill a container such as a dustbin with alternate 7.5-10cm (3-4in) layers of 2-3 year-old leafmould and chopped comfrey leaves. Use when the comfrey leaves have virtually disintegrated.