There seems to be some controversy about whether or not to rake up your leaves in the fall. I have come across several articles putting forth conflicting points of views. I am going to try to sort through the information and deliver some of the facts so that you can decide what you want to do.
Last weekend in The Toronto Star an article entitled “Mid-autumn garden tasks are key” written by Mark and Ben Cullen stated that the thing not to do is to blow your leaves into a pile, put them in paper bags and ship them off with the city pick up. He put forth that an alternative is to rake them into your garden where they will provide free mulch, and some winter protection from cold and snow. If you leave them on the garden over the winter, the earthworms will pull them down into the soil creating nitogen-rich earthworm poop. The article also says that if you have too many leaves, run the power mower over them before you put them in the garden. I read this and thought it seemed like very sound advice, until I came across an article entitled “Leave The Leaves” published by the Xerces Society. This article tells us that many butterflies and moths overwinter in the form of an egg, caterpillar, chrysalis or adult in leaf litter. In addition to this they suggest that bumble bees, spiders, snakes, worms, beetles, millipedes, mites and many more winter in leaves. They argue that shredding the leaves destroys the eggs, caterpillars, and chrysalis that are harbouring there for the winter. They suggest that leaves in garden beds and along the edges be left whole. They also suggest that you can create leaf piles that will break down naturally or that can be added gradually to your compost heap over time. This will keep the critters safe and also allow you to benefit from the leaves.
What about leaving leaves on your lawn? There is the argument that you can grow snow mould which is a pink or gray fungal disease that can attack your grass. This is likely only if you have a ton of leaves and they are covered with a mounds of snow all winter. An article entitled “Improve Your Soil By Raking Less” posted on finegardening.com suggests that research done at several universities proved that nutrients from leaves mown into lawn areas improves turf quality. At Michigan State University, a rotary mower was set to cut at a height of 3 inches then mowed an 18 inch deep layer of leaves (equivalent to 450 pounds of leaves per 1000 square feet), left on top of test plots of turf. The results were an improved soil, healthier lawn and few remnant leaves visible in the spring. They suggest you can do the same by setting your mower to 3 inches, mowing at least once a week during peak leaf fall preferably after a light dew. According the article, you will never have to rake another leaf while at the same time improving your soil quality.
Another suggestion made by the article posted on finegardening.com is to rake your leaves onto your empty annual garden beds, shred them with a lawn mower, sprinkle them with a 1 pound coffee can of 5-10-5 fertilizer per 100 square feet of garden, turn the leaves and water thoroughly to disperse the fertilizer. Turn the leaves again in the spring and plant directly through the remaining clumps. They will provide nutrients as they decompose. This is a good option, but does not address the wildlife you are destroying by shredding the leaves.
While sifting through these articles, a few things stand out. First and foremost, it seems the worst thing you can do is rake up the leaves and get rid of them. There are numerous ways to utilize the leaves in your garden. The part that I am still concerned about is how we manage the volume of leaves without shredding them.
The Xerces Society article argues that after you spend the summer providing flowers and place to rest for butterlies and other critters, you tend your garden and avoid pesticides, and then you throw out your leaves like trash, you are throwing out the same butterflies and moths that you worked so hard to attract.
They also suggest that if you do decide to “leave the leaves” intact over winter, but must rake the lawn in the spring, do so late in the season in order not to destroy the critters who have overwintered there.
Making a decision about how to handle your leaves, will be up to you. Consider that much of what we do is based on habit, social conditioning, or a holdover of outdated gardening practices. Choose an option that works best for you and keep in mind the moths, butterflies and other critters that depend on your leaves for winter protection and try to allow some of your leaves to remain intact and in place for them.
Mid-autumn Garden Tasks Are Key: Mark and Ben Cullen, Toronto Star, October 21, 2017
Leave The Leaves: xeres.org, 2017/10/06
Improve Your Soil By Raking Less: finegardening.com, Fine Gardening issue 117