Raking leaves is a tedious task that is best forgotten. Fortunately for us, both environmental groups and gardening experts tell us to leave them where they fall in our gardens. But can you really forget about fall cleanup and leave those leaves in your flower beds?
Should I leave leaves on flower beds over the winter?
Yes, it is advisable to leave fallen leaves in flower beds during the winter. A layer of leaves will protect beneficial insects, beneficial microbes, perennials and bulbs. The leaves decompose to return nutrients to the soil. Prevent leaf buildup from smothering growing plants and evergreens. Remove leaves from a diseased or pest-infested tree.
Leaving fallen leaves in flower beds during the winter has lots of benefitsincluding:
- Protect bare soil from erosion,
- Protect beneficial insects and microbes in the soil.
- Protect beneficial insects that hibernate in leaf litter,
- Protect bulbs and perennials, and
- Return nutrients to the soil as they decompose.
However, plants still need light and air circulation, especially those still growing in the fall or evergreen plants that grow during the winter. If the leaves pile up so high that you cannot see the plant, then you should uncover the plants and move the extra leaves to another location.
For added safety or if the leaves are very large (like a sugar maple), You can shred the leaves into smaller pieces. Mulched leaves decompose faster, so it is best to mulch them.
But mulching leaves also means you’re destroying any insects that are using the leaf litter for winter cover or to lay their eggs (including many beneficial insects like ladybugs). Moving these leaves to another location on your property can keep these beneficial insects safe without suffocating your plants.
When should you remove leaves from flower beds?
For the most part, it will not be necessary to remove leaves from flower beds. But there are some cases where you will want to do this, such as if the leaves have accumulated too much (removing only the excess), if the leaves are diseased (more on this below), or if you are sowing seeds.
If you have a black walnut tree, remove black walnut leaves from any garden beds that have non-hardy plants. Fall black walnut leaves have less juglone than spring leaves, and considerably less than roots, but still contain juglone. Instead, toss black walnut leaves into a well-managed compost bin. By the time the compost is ready, the juglone should be gone. You could leave the leaves in place if they decompose quickly enough, but composting is faster and safer.
Should you remove leaves from flower beds in spring?
It is not necessary to remove leaves from flower beds in spring, as long as they do not suffocate the plants there. If you are planting new annual seedlings, you can even gently move the leaves as you plant before returning them to the new plant. If you start from a seed, keep the leaves off the ground around the seed until they can sprout.
The spring bulbs should be able to push themselves out through the leaf litter, or even a layer of bark mulch. If the layer of leaves is still very thick, you can gently rake them to separate them from where the bulbs will emerge.
If you normally cover your garden beds with mulch, you don’t need to remove the leaves first. You can just mulch on top.
If you decide to remove leaves or mulch in the spring, wait until daytime temperatures consistently reach 50°F (10°C). This gives beneficial insects enough time to wake up or hatch beneath the leaf litter and soil. Meanwhile, you still have a layer of mulch in place, so you get the benefits of mulch or a ground cover without accidentally blocking the exits of overwintering insects in the soil by applying mulch too soon.
Will the leaves decompose during the winter?
While cold will slow or stop decomposition, a thick layer of leaves (more than 4 inches) can still decompose into a thin layer (1 to 2 inches) during the winter. Leaves also have the benefit of shoulder seasons, when it’s too cold to do anything in the garden, but warm enough for decomposition to catch up. The leaves add a layer of insulation, so decomposition can occur even when you can’t see it. And when spring comes, your soil is still covered and protected by the remaining leaves.
Even in the best conditions, leaves take longer to decompose. Some species are faster than others, depending on their lignin content.
Can there be too many leaves in the garden soil?
Technically, If you bury leaves, You may have too many leaves (or carbon sources) in your garden soil. If there are too many leaves and not enough nitrogen sources, the leaves will block the available nitrogen in the soil from being decomposed. There will not be enough nitrogen available for growing plants.
But the solution is easy. Just don’t bury leaves in your garden soil. Leave them above the ground, where they don’t have access to most of the nitrogen and can provide you with all the benefits mentioned above.
If you still want to bury them, bury them with enough nitrogen sources (like kitchen scraps) to make up for the rest.
A few leaves accidentally getting into a planting hole or flapping around during rototilling won’t make much difference, so don’t worry. You will only have problems when you bury many leaves.
Do fallen leaves harbor pests or diseases?
Like most natural gardening, using fall leaves as mulch is a double-edged sword. Fall leaves protect pests as much as they protect beneficial insects.
If the parent tree has been infected with a disease or pest, play it safe and remove the leaves from your garden.
Otherwise, just make sure the leaves don’t smother your plants, work to attract beneficial insects, and enhance beneficial microbes in the soil. Balance is key. If you have enough beneficial predators, they will keep pest populations in check. Likewise, healthy soil helps plants be healthy, and when plants are healthy they resist disease better.
Final thoughts
Autumn leaves can be a great ally for the health of your flower beds. By leaving them in place, you are imitating nature and protecting your beneficial plants, insects and microbes. Just make sure the leaves don’t pile up high enough to block evergreens or still-growing plants, and don’t bury them in the soil.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden center helping people buy plants, gardening supplies and lawn care products. He has experience in real estate and is a homeowner. Jamie loves garden projects, finishing furniture and likes to share his knowledge online.
