How to put fallen leaves to work in your garden

Early in March, when it still felt like high summer, the lipstick maples in my street started turning an autumnal pink. A month later – with the days still summery – the maples were almost magenta. Now these trees have upped the ante and turned pure purple. Lucky, then, that you can finally feel autumn in the air.

The sun is softer, the nights are longer and at last the maples feel like they are in seasonal step. Other trees are joining the fray. Pin oaks have turned scarlet, ginkgoes are yellow and beeches are flashing red. Blazing leaves are catching your eye at every turn.

At this time of year, many deciduous trees put on a spectacular show, transforming neighbourhoods.Credit: Getty Images

And you don’t even need your own garden to enjoy the drama. One of the best things about autumn is how you can enjoy its colour from afar – over fences, down streets and across parklands. It’s not shy.

Public gardens (such as Centennial Park in Sydney, Carlton Gardens in Melbourne and the botanic gardens in both cities) flaunt some of the grandest theatrics in town. While warm weather lowers the intensity of autumn colour, these landscapes have so many deciduous trees – and shrubs and climbers – that they still pack a punch.

But for the hottest hues you have to head to more mountainous spots (the Blue Mountains in New South Wales, and Mount Macedon in Victoria, say) where the cooler climates make for especially vibrant yellows, oranges, reds and purples once a leaf’s green chlorophyll pigments break down. These autumn-leaf hotspots always lure big crowds once the season gets going in earnest.

For gardeners, the magic of autumn foliage has never been restricted to appearances. The feelings of delight these leaves engender also lie in the rot and decay that comes next. This is the season of decline and a dead leaf can be put to good use.

Fallen leaves have their own beauty but not everyone appreciates where they land.Credit: Getty Images

Fallen foliage can improve the make-up of your soil and the health of your plants. While trees reclaim the leaves’ most beneficial nutrients before shedding them from their branches, fallen leaves are still well worth holding on to.

Rather than sweeping them up, piling them in bags and sending them off as green “waste”, devote your energies to feeding this free resource to your garden.

There are all sorts of ways to do it. The easiest is to take your cue from natural forests and take no action at all, letting the leaves stay where they fall and slowly break down.

But chances are they won’t all drop in the right places. Some will end up on paths and paving, others will form thick blankets that smother low-lying plants and prevent rain from penetrating the soil. Most of us will want to move our leaves about.

But there is no need to go overboard. By leaving at least a scattering of leaves over garden beds you create habitat for insects and other life forms while also mulching your soil. Worms will work them down deeper as they slowly break down.

As for the leaves you do remove, pile them into wire cages or plastic bags – with holes punched through to keep things aerated – and put them in a shady spot. Keep the leaves damp but not all-out wet to encourage decomposition.

While the leaves of some trees (such as elm) break down faster than those of others (such as plane) it generally takes at least a year for the leaves to reduce into a relatively fine, crumbly leaf mould. You can accelerate the process by first shredding the leaves with a lawnmower. By adding blood and bone, which is rich in nitrogen, you can speed up the decomposition process even more. But it is not instant, and, like making compost, it does take up outdoor space.

If you don’t have a lot of leaves, you can also just add them to your compost – which is made up of materials containing both carbon (autumn leaves, straw, paper) and nitrogen (food waste, grass clippings.) But you might have too many to fit because, before they break down, these leaves take up a lot of room.

On decomposing, they turn into a more dense concoction that can be worked into the soil to improve its structure and to help it retain water and nutrients. Leaf mould also encourages worms and mycorrhizal fungi.

It will work such wonders that the haul from your own garden won’t appear enough. Soon you will find yourself collecting other peoples’ unwanted leaves as well.

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