By Pamela Walker and Carolyn Herriot
Published in TAKE 5 Magazine, October 2021
Soil, on which all life outside the ocean depends, has been created in part by thousands of years of falling leaves. As they fall down, life rises up. It’s the perennial gift that keeps on giving, but a resource that is often overlooked. After a year of drought we should all be stockpiling leaves to use as a protective mulch for next year’s garden. Broken down leaf mould can hold 300 to 500% of its weight in water. Rich topsoil, by comparison, holds about 60%. Leaf mulch holds in moisture, adds organic matter to the soil and provides nutrients to plants. It’s as precious as bullion to plants and beneficial insects, so whatever you do, don’t burn leaves or throw them away in a large plastic bag!
What colour is a leaf? Most would say green, but green is actually the colour of chlorophyll, the pigment that enables leaves to change light into energy. A leaf’s true colour is yellow, red, orange, or gold.
Are leaves good for composting? Some leaves are better than others. Large trees such as oaks, maples, sycamores and chestnuts are wonderful sources of nutrient-rich leaves which will easily break down into compressed leaf mould, high in humus, worm casings and plant nutrients. Maple leaves are fantastic, being high in calcium and potassium, and our area abounds with native big leaf maple trees, with masses of large leaves shed each year.
Holly and arbutus leaves have a waxy cuticle, which means they longer to break down, so it’s best not to base a leaf mulch on them. If you have pine or fir trees, compost these needles separately. They produce an acidic leaf mould that is excellent for ericaceous (acid-loving) plants such as azaleas, rhododendrons, pieris, hydrangeas, blueberries, heathers and camellias. Walnut and cedar leaves should be avoided, since they release chemicals that suppress the growth of other plants. Don’t save leaves (fruit trees are especially prone) showing signs of disease, such as rust, black spot or mildew, since pathogens present may survive. Tip: Dig a hole and bury them in the garden, where microbes will get to work destroying them.
What is the best way to collect leaves? The dream way is for the wind blow them into a corner. A heap of leaves will break down into a pile of rich, crumbly leaf mulch in one year (faster if you turn the pile). Shallow-rooted plants such as rhododendrons, azaleas, camellias, hydrangeas, pieris, skimmia and heathers just LOVE leaf mulch. Leaf blowers are horrible to crawling and flying insects. Just grab a good old garden rake and get a good aerating workout! It’s satisfying work, and using a tarp makes moving a big pile of leaves easy. Reduce a pile of leaves by spreading them out on the driveway or lawn and running your lawn mower over the pile, on the highest setting. This reduces the pile to a tenth of its volume, and it can then be sprinkled onto beds, where it quickly breaks down to feed the soil, without blowing away.
Don’t position leaf piles under trees or hedges where fibrous roots will grow into the pile. If you must, put landscape fabric down first as a barrier. Tip: Store dry leaves in bags or wire cages and use for layering into compost throughout the year. A circular cage of fencing wire, or four posts wrapped with chicken wire, is a simple space-saving way to store leaves.
Leave a portion of your property unraked. Mother Nature loves a bit of messiness. Caterpillars will crawl under the leaves to form their cocoons, while ants and other crawlies will lay their eggs, providing food for the birds. Worms spend the winter under a shallow mulch of leaves, adding worm casings to the soil, and improving soil aeration.
This fall the Ladysmith food bank garden at Kiwi Cove Lodge needs lots of garden leaves to improve the garden soil. If you have bagged oak, maple or chestnut leaves please drop them off at the garden behind the lodge. If you would like someone to collect your bagged leaves, email the Yellow Point Ecological Society, firstname.lastname@example.org.