I love walking through fallen leaves in September. I kick them up, crunch them down, and take joy in the sound, sight, and smell of the changing seasons. Beyond the majesty of fall’s displays, fallen leaves provide me a practical use too.
I hate picking up raked leaves – they make me sneeze and always try to escape my grasp – so I am glad to have an alternate use than throwing them all in my green bin. Leaf litter makes an excellent mulch to help plants survive our temperamental winters
The cold of Calgary’s winters is broken by our chinook winds. They provide a nice respite from the snow and ice, but they can also be killer for our perennial plants. Many plants rely on consistent snow coverage to remain dormant through the winter. With the frequent freezes and thaws that Calgary experiences, it can be tough for perennials to survive, especially if they are imported cultivars, such as most available at hardware stores. To help our plants thrive, we can protect them through the winter by mulching them in fall to keep soil temperatures more consistent through the winter and early spring.
Using fallen leaves as mulch
Mulching can be as simple as raking your leaves directly onto the soil of your garden. If you need a quick fix to the leaves on the lawn, this can do you well. However, this route comes with two primary concerns: first is that you will have more cleanup in spring, as you have to remove the wet leaves. I do personally find this easier than moving the dry leaves in autumn, as the leaves pick up in clumps. The second problem is that if you apply the leaf layer too thickly, then you may actually cause harm to your soil, as air and moisture cannot transfer, potentially leading to sodden soil. Use full sized leaves sparingly, and in exposed areas where the soil really needs the thick protection.
To maintain a simple solution and provide the benefits of the mulch, simply rake your leaves towards your garden beds, then run your lawn mower over the pile a few times. There’s no need to pulverize the leaves completely, just break them up. Then rake this pile over onto the garden bed. The shredded leaves will have a greater surface area, encouraging healthy microbial growth, and will also have spaces in between for air and moisture to penetrate.
In addition to protecting your soil and plants from freezing and thawing repeatedly, leaf mulch also provides a winter home for the ever popular ladybugs. They winter in layers of leaf mulch or similar structures (like your house’s siding!). By protecting your plants, you are also providing a home to these helpful hunters.
A caution for shade
Leaf mulching is excellent for protecting exposed areas of your garden. But where there is more shade and less wind, you may find that the mulching is not necessary. In parts of your garden that maintain consistent snow coverage, the freeze-thaw cycle is of less concern.
I have found that leaf mulch in shady corners remained frozen too long, and my early spring bulbs could not emerge. Instead of keeping these corners in deep freeze, you could consider leaving the soil bare. This provides a different wintering habitat for favoured garden insects. Ladybugs can winter in the leaf mulch, while queen bees will find the shady soil a perfect home for the winter, and can emerge to keep our spring apple trees well pollinated.