Leaves, leaves and more leaves
The nights are drawing in, and the trees are preparing for winter dormancy. The brilliant colours that we all delight in are caused by the green chlorophyll disappearing from their leaves. As the bright green fades away, the yellow and orange colours become more visible. Small amounts of these colours are present in the leaves throughout the year but are just not seen in the summer, because they are covered up by the green chlorophyll. The bright reds and purples in leaves are made mainly in the autumn. In some trees, like maples, the glucose is trapped in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn cause this glucose to turn a red colour.
There is not enough light or water for photosynthesis as the days get shorter, so they rest and live off the food they stored during the summer. They begin to shut down their food-making factories and the leaves fall from the trees as they are no longer required.
These leaves are a precious resource for the gardener as all leaves and conifer needles will eventually break down into leaf mould. Some leaves, such as oak, beech or hornbeam, break down with little assistance and produce an excellent quality product.
Thick leaves like sycamore, walnut, horse chestnut and sweet chestnut need to be shredded before adding them to the leaf mould pile, as they are much slower to break down. Alternatively, they can be added to the compost heap after shredding.
Evergreens such as holly and cherry laurel, are better shredded and added to the compost heap, where they will break down faster than if added to the leaf mould pile.
Conifer needles will eventually break down, but may take two to three years to decay. Conifer hedge clippings are better added to the compost heap than used for making leaf mould.
Pine needles are worth gathering and placing in a separate leaf mould pile as they produce acidic leaf mould, which is ideal for mulching ericaceous plants.
Whatever leaves that you have available, collect them in autumn and either place in bags to breakdown or build yourself a leaf bin and wait for the magic to happen. When they are soft and crumbly it is ready to use. If you have a limited amount then use in shady areas to mimic woodland conditions.