Autumn is upon us, and soon a dazzling display of fiery foliage will set our gardens, parks and countryside ablaze. But when those luminous leaves fall, what are we to do with them? At their worst, fallen leaves can be slippery and suffocating, yet with a little effort, you can transform them into valuable leafmould, marvellous mulch, rich compost or even decoration for your home.
Here are five of my favourite things to do with an excess of autumn leaves.
1. Make an autumn wreath.
I’m not a fan of Halloween, but I’ve loved decorating for autumn since collecting pretty leaves in the park for my primary school nature table. Trees such as the tulip tree (Liriodendron tulipifera), northern red oak (Quercus rubra), sweet gum (Liquidambar styraciflua) and sugar maple (Acer saccharum) produce startlingly beautiful leaves combining interesting silhouettes with intense autumn colouring. Some, such as katsura (Cercidiphyllum japonicum), even have a delicious scent, reminiscent of burnt sugar and candyfloss.
I amuse myself by gathering armfuls of leaves that interest me and place them in a large bowl, or sometimes I scatter them artfully down the middle of a dining table. If you have the patience, you can attach larger leaves to a wreath base (moss, vine or wicker will do) using a darning needle and thick cotton thread to create a sustainable decoration for your front door. When the colour fades or you’re ready for a change, the whole thing can be composted. If you’re feeling ambitious, you could fashion boughs of crab apple, hawthorn and oak into a wreath or garland, selecting branches that retain enough flexibility for you to coax them into a pleasing shape.
Top Tip - gather leaves for decorating soon after they’ve fallen for the cleanest, brightest colours. If you’re foraging in a public park, be mindful of what could be lurking in the leaf litter and wear gloves as a precaution.
2. Create a wildlife refuge.
Wild creatures adore a leaf pile. If you do nothing more than gather your leaves into a large heap in an undisturbed area of your garden, they will love you for that!
It’s fine to mix deciduous and evergreen foliage with twigs, dried grasses and bark to create an open, varied structure, appealing to a variety of insects, amphibians and mammals, including ladybirds, spiders, caterpillars, toads and hedgehogs. If you’re feeling adventurous, you might even want to experiment with different blends to see what attracts the greatest diversity.
Don’t be too concerned if slugs and snails also take refuge in your leaf pile - they are expert composters and generally prefer munching decaying material to fresh. They’re also a great food source for frogs, thrushes and slow worms.
Top Tip - if you are concerned about dry leaves blowing around the garden after you’ve spent hours collecting them up, create a cylindrical bin using chicken wire and pop your leaves inside that. As soon as they get wet and start to decay, they will hold together and cease moving. If you don’t have chicken wire, make a teepee around your heap using short canes or branches. Push them firmly into the ground at an angle before tying them tightly at the top with twine.
3. Turn them into black gold.
Leafmould is a fine, crumbly, lightweight material made exclusively from decayed leaves. Rich in humus, you can use it as a soil conditioner and an ingredient in potting compost. Gardeners often refer to leafmould as ‘black gold’ because of its dark colour and generous nutrient content. In a future where we won’t use peat, leafmould is a renewable alternative that retains moisture and improves soil structure. It’s also free, provided you have a plentiful source of leaves, and you'll rarely find it for sale as it's too precious!
Leafmould is created by allowing leaves to decay over a long period of time, usually two years. Unlike composting, which is facilitated by bacteria, the formation of leafmould is aided by fungi - hence the ‘mould’. There are many ways to make it, from simply piling leaves in a heap and letting nature take its course to buying special bags with a loose weave that permit good air circulation - these are ideal if you are short of space. Free of other garden waste, leaf mould is generally weed-free.
The best trees for making leafmould are oak, beech and hornbeam as their foliage is thinner than many other trees, meaning that it breaks down quickly. The thicker foliage of sycamore, walnuts, horse chestnuts and sweet chestnuts is best shredded or chopped to help speed up the transformation. Best avoided altogether are the waxy leaves of evergreens such as holly, holm oak and bay - add these to your compost heap with grass clippings and other green waste. You can make leafmound from pine needles, although it may take more than two years to achieve the right texture. The resulting leafmould will be acidic, which is ideal as a mulch or soil improver for plants such as rhododendrons, camellias and heathers.
Top Tip - Unlike composting, making leafmould does not require heat. Cool, damp conditions are ideal for fungal activity, so build your heap in a shaded corner of the garden or store your bags against a north-facing wall, checking occasionally to ensure they don’t dry out.
4. Leave them to feed and condition your lawn.
Experts disagree on how much harm is caused by allowing fallen leaves to carpet your lawn. Let common sense prevail, and if the layer is so thick as to block light and air from reaching the grass, thin it out or move the leaves onto neighbouring beds and borders instead (see below).
A light scattering of leaves will cause no damage and is best handled by mowing with the blades set high on a dry day. This simple action will chop the leaves into smaller pieces, helping them to decompose more quickly. This, in turn, will feed the lawn, and the humus will enhance drainage and improve water retention during dry spells.
Top Tip - One situation where you mustn’t over-enrich your grass is where you’re hoping to establish a diverse, wildflower meadow. Too many nutrients will encourage an invasion of thugish thistles, nettles and docks, so relocate the leaves to the compost heap or neighbouring beds.
5. Use them as a mulch
In the countryside, leaves from individual trees, hedges and woodlands fall to their base and stay there, or thereabouts, completing a natural cycle and creating a habitat for a unique cohort of creatures. If it can be managed, this is the best way to proceed in your garden, too. Not only does leaving leaf litter in situ reduce time and effort, but there is research to suggest that it benefits plant health and biodiversity.
Again, use common sense, and if a deluge of fallen leaves is smothering your prize cyclamen, one or the other needs to be moved! Most plants won’t enjoy having a mound of leaves on top of them, or closely hugging their sides, so gently nudge the litter to one side so that air can flow freely around them.
Top Tip - By all means, sweep up the leaves from the pavement outside your house, but think twice about using them as mulch. The UK Environment Agency found that compost produced from leaves that fell from street trees contains high levels of polycyclic aromatic hydrocarbons. These are byproducts of fossil fuels such as petrol and diesel, and are persistent pollutants. The compost may also contain traces of salt, grit, plastic, metal and glass that make it undesirable for use as a mulch, especially where you’re growing edible plants.