Fall cleanup: What to do with all the leaves?

To rake or not to rake – that has been the eternal question for homeowners every fall. Conventional thinking has always leaned toward picking up leaves; however, environmentally-minded folks make a good point when they claim that leaf litter is a natural compost and you should just leave leaves where they fall.

Both sides are right. The trick is, we need to reframe our fall clean-up thinking to reflect what it is we’re really doing -- we’re closing down our gardens and tucking them in for the winter. The goal is to stage your garden to help it transition into dormancy in the most supportive way so it can withstand whatever forces of winter are thrown at it.

When you begin thinking of fall cleanup more like the tuck-in service you might get at a four-star hotel, you’ll begin treating your garden a little more gently. In a way, your actions will be more like pampering it and tucking it in for the long winter night. This reorientation will affect your decisions about removing dead leaf litter or just leaving it where it lays – you’ll discover it’s not a simple question with a yes or no answer.

Here’s why.

All gardens and the plants within them are different. Their composition and location greatly affect how you treat them and prepare them for winter. Those on the sunny, more protected south side of your home require different treatment – tuck-in service, if you will – than those on the more exposed north side. As a result, you and your gardens may be better off removing leaves from one while leaving them for protection and nourishment in another. So the questions become “what kind of leaves do I have?” and “what type of garden?”

The beautiful autumn foliage has to fall at some point. You get to decide how much to intervene.

The reason to ask about the types of leaves that are present is to determine how they break down so you can get a better idea of what to do with them. For example, oak leaves and pine needles do not break down quickly. There is a lot of carbon in them, and they are acidic and will persist in the landscape for a long time. If the leaves are maple or birch, they are thin and will break down and rot more quickly.

The leaves of ericaceous plants -- broadleaf evergreens such as azaleas and rhododendrons -- are very hard because they have a gloss on them and will not break down quickly. Perennials and deciduous shrubs such as roses, hydrangeas, dogwoods, and lilacs feature leaves that are fleshy and will break down more easily, but if you have gardens with those plants, you may be looking for a neater environment.

My pollinator garden now gets cut back about 90% to protect it from the voles!

Leaves are, in fact, a clever tool devised by Mother Nature to perform a variety of functions. They help plants get and store energy, moderate temperature, and provide food for insects and animals. But they also act as a carrier for disease and harbor pests. For example, powdery mildew likes peonies, lilacs, and phlox to name a few hosts. Not only do you need to pick up their leaves, but you also need to dispose of them – and NOT in your compost, where the leaves will break down and spread the pathogen.

Remember that nothing exists in isolation in nature. Landscapes and the plants within them are inextricably bound together, interacting both visibly and invisibly. What is the nature of the landscape or garden where the leaves are falling? Are there acidic oak leaves falling onto ericaceous plants such as azaleas that are perfectly happy in acidic soil? Or does the garden in this area face south with a collection of plants that prefer a sweet (more alkaline) soil?

Blackeyed Susans are beautiful with snow cover. Be prepared to weed out all the new seedlings next spring.

When you leave leaves in the garden, you protect the ground and support the soil biology, but you may also create an environment that enables harmful insects and rodents, such as mice and voles, to winter over, which can be problematic for you and your garden.

To leave or not to leave.

Perhaps the best way to answer that effectively is to test different areas of your garden or gardens to determine whether to remove leaves or leave them alone.

One year I tested the idea and let the leaves fall and stay in my pollinator garden, planning to clean things up in the spring. The mess was something I had to get used to, but I patiently waited for winter to pass. It was actually really pretty that winter with snow on it.

When I finally cleaned up the garden in the spring, I was dismayed to find no less than 35 or 40 of my perennials were partially or completely eaten by voles, a sort of tailless mouse that does not hibernate. The meadow vole is highly active in the winter, creating a network of tunnels safely under the snow where they shear off the bottom of grasses and other plants. And they weren’t alone. I also had tree voles, which go after the bottoms of trees and shrubs, chewing bark, cambium, and roots for nutrition effectively girdling the plants. There had to have been up to 100 voles in the garden.

Astilbe chinensis 'Pumila', Ilex verticillata 'Winter Red', and Pleioblastus viridi-striatus all shine with a blanket of snow. 

The lesson I learned was that when you deal with a highly visible, managed, or coveted parts of your landscape, the best bet may just be to pick up leaves to avoid damage that may be deadly to your plants and devastating to you in the spring. You aren’t aiming for perfection (not a leaf in sight). You’re aiming for a level of cleanliness that discourages borrowing and nesting. In areas further away from your home that are less visible and less managed you might let the leaves fall where they may.

Remember, if you are going Native, No touch, Natural - then you aren’t likely adding plants to your garden the way I do...so maybe leaving the leaves is just okay. Me...I’m looking for a mix of the native, the cultivated, the pollinators, and the flowers. I’m asking for a lot out of my gardens, so I think a lot before I act. Now, I clean that garden up and I still have gobs of happy bugs and birds all through the growing season.

Before you decide between breaking out the rake or leaf-blower or staying in to watch the game or baking a yummy batch of cookies, think a bit about the types of leaves that are falling, the kind of gardens you have, and what your looking to achieve. Ask, what will happen if I do nothing? Weigh the benefits against the detriments and then answer the question once and for all: “What do I do with all the leaves?”