by Brianna Flavin, Ramsey County Master Gardener
9/22/24
(photo credit: Brianna Flavin)
It’s easy to love autumn in Minnesota! Whether you’re a fan of the changing fall colors, apple orchards, the festivities of Halloween and Dia De Los Muertos—or just the relief from high temps in the hot sun—getting outside and enjoying the cooler air is a pleasure this time of year.
Fall also brings its own yard and garden chores, the most iconic of which is definitely raking leaves. You might have heard lots of contradictory advice about how to handle the leaves that fall onto your lawn and garden.
Rake and bag the leaves before the snow comes! Reduce cleanup for pollinators. Just let the leaves lie where they fall! Don’t let your tree leaves clog the storm drains and waterways! Why would you pay someone to haul away useful compost?!
All of the advice we hear can get confusing. There are a few environmental considerations to weigh when choosing what to do about autumn leaf litter, but making the right choice is dependent on your situation.
Here are a few leaf cleanup guidelines to follow in Minnesota, along with some suggestions for making yard and garden chores as sustainable as possible for you and your garden.
1. Don’t let leaf litter build up in storm drains. Many Minnesota properties include trees on the edge of a lot, right over the street and storm drains. This can become a problem when an excess amount of leaf litter washes into the storm drain system and builds up in local lakes.
Lakes are used to absorbing the leaves that fall from trees near the waterline, but when piles and piles of leaf litter from drains wash in, the corresponding rise in different minerals, not to mention pesticides or pollution, changes water pH and quality. This can be damaging to the delicate ecosystems of our lakes.
The Minnesota Pollution Control Agency asks Minnesotans to rake up the leaves that fall near streets and alleys and to sweep leaves out of the street. Some cities (like Saint Paul) have street sweepers that come by in autumn for this very reason.
2. Don’t let leaves blanket more than 10-20% of a turf grass yard. Mulched leaves can be a good addition to your grass, but there’s a limit to how much you should allow. According to the University of Minnesota: Turfgrass Science, you should rake leaves away from about 80-90% of your lawn.
If you have a large swath of fallen leaves covering your grass, they can inhibit growth and kill the grass underneath as the weight of snow presses them down all winter. The extra moisture and insulation from a carpet of leaves can also increase the likelihood of snow mold disease on your grass.
3. Do mow scattered leaves into your turfgrass. A sprinkling of chopped-up leaves is great for your lawn! If you happen to have a legume-family tree like a locust, the leaves that fall from it can be rich in nitrogen, offering extra fertilizer for your grass.
If you have a mulching lawn mower, going over a carpet of leaves a few times can break everything down small enough to feed your grass without causing problems. But if you have a fairly thick carpet of leaves to deal with, some raking is probably in your future.
4. Do rake up and compost heavy piles of leaf litter. If you have a large wooded property, the only reason you should consider raking is when you have diseased plants or concerns about fire susceptibility. Leaves that fall on a forest floor provide a critical habitat for wildlife and native plants.
A carpet of leaves can be damaging to turfgrass, and significant leaf fall might be too much to attempt to mulch into your lawn. In this case, raking up the leaves and composting them (or bagging them to be hauled away) is the best way to take care of your grass.
If you have the space, creating a leaf mold pile can be an easy and sustainable option. Leaf mold (rotted leaves) is a useful source of nutrients and a great addition to soil texture for your garden. Plus, it’s hard to beat the convenience of dumping all your leaves into one spot onsite.
Try making a simple DIY leaf mold cage. Dump your extra leaf litter inside and wait a year or two. Then you can use the leaf mold like you would a regular compost.
Many cities and counties in Minnesota also have local compost and yard waste sites you can utilize, and many of them for free! Find your local site and bring your extra leaves for composting. Check out this Minnesota Compost Site Map run by The Minnesota Pollution Control Agency to find a site near you.
5. Do use leaves to mulch your garden beds. Fallen leaves make an excellent insulator for our gardens. Despite the mild winter we had last year, the lack of snowfall as an insulator may have led to damage to plants that will need a little extra winter protection this year. Strawberries are one example of a plant that benefits from some extra insulation in the winter. Covering them with the eponymous “straw” is perfect if you have it. But leaf litter works just as well!
In my city lot, I don’t have a significant drop of leaves to handle in the fall, but I rake what I do have into my garden beds, especially those near the boulevard or paved surfaces, as an added source of insulation and moisture regulation.
Whatever you love most about being outside in autumn, set aside some time to interact with the leaves in your grass and garden. Come springtime, you’ll be glad you did!
References
Bio: Brianna Flavin is a Ramsey County Master Gardener intern living on St. Paul’s east side with her partner and two young children. She’s especially into berry plants and budget-friendly solutions for making small gardens productive, beautiful and beneficial.