Fall Cleanup

Fall Cleanup by Laura Rodger, Grand Erie Master Gardeners

It is that time of year when most of society expects us to start our fall cleanup. But as we are starting to learn more about the importance of gardening for nature, a lot of the old recommendations are changing.

Essentially, the new recommendation is “LEAVE THE LEAVES.”

Why?

Many caterpillars and other insects like lighting bugs overwinter in leaf litter. When you rake up the leaves and put them in bags to be disposed of, you are killing many of these native insects.

Why should I care about caterpillars?

They turn into moths and butterflies which are important pollinators. The caterpillar stage is also an essential food source for baby birds in the spring. In North America, 96% of bird species rear their young on soft, nutrient-filled caterpillars - not seeds, berries or hard-shelled beetles.

Many caterpillars start out their lifecycle on the leaves of the tree, but then need to drop down onto the ground and bury into the soft ground under the leaf litter or in the leaf litter itself over the winter. If you rake up the leaves under your trees and leave hard compacted soil in place, you are interrupting the life cycle of these insects and by extension killing important native pollinators.

Did you know that many native caterpillars are plant specialists? This means that, just like the monarch caterpillar which can only eat plants in the milkweed family, most caterpillars can only eat specific native plant leaves. This is why growing native plants is so important.

How else do leaves help my garden?

Leaves also break down and add nutrients to the soil. Most woodland plants require nutrient and humus rich soil to thrive and survive. If you rake up the leaves you will be leaving hard compacted soil, which will not provide a good habitat for shade loving plants. You will end up having to bring in compost and mulch to try to get anything to grow, costing time and money.

A thick carpet of leaf litter also acts like a sponge during rains and decrease run-off, which is especially beneficial during heavy rains.

What about plant stems?

Another easy one: “LEAVE THE STEMS STANDING OVER THE WINTER”.

Many flowering plants leave seed heads which provide food for overwintering birds. The stems are also often used by native bees. The female bees find cut or naturally occurring open stems, create a nest inside, then lay an egg on a pollen ball. The eggs hatch to become bee larvae and they eat the pollen.

Did you know that many native bees are pollen specialists? This means that they have evolved to only be able to use the pollen from specific native plants to raise their young. Another excellent reason to choose native plants for your garden.

But what about the lawn?

A thick layer of leaves on your lawn is probably going to smother it. So yes, you will need to rake the leaves off your lawn and place them onto your flowerbeds. If you have grass under your trees (which may be struggling due to roots and shade), consider creating native plant beds under your trees. This will provide “soft landings” for caterpillars and other insects and save you time and effort raking the leaves since you can just leave them there.

Can I use my lawnmower to shred my leaves and then put them on my flowerbeds so they break down faster?

The leaves will indeed still help feed the soil this way, but you are also shredding the insects so it is best to just gently rake the leaves whole onto the flowerbeds instead.

What about my super fun leaf blower? Sadly leaf blowers also kill insects. It really sucks.

My neighbours have bags and bags of leaves set at the curb - can I add them to my garden?

Maybe… if you don’t have enough leaves this could be a good source for more, assuming they are disease-free and do not contain invasive plants. Plus when you explain to your neighbours what you are doing, maybe they will decide to start leaving their leaves in place too. But do not pile 2 feet of leaves onto your soil if you already have plants growing there. Plants do need to be able to get through the leaf litter in the spring, so try to keep it to a couple of inches. Or create a leaf pile in a corner of your yard that can break down into a rich humus that can be added to your garden in a year or two.

What if the stems in my garden are leaning and falling and looking way too messy for my front yard?

Well, if you live in town you do need to keep your front yard looking intentional - consider cutting those stems down and dropping them where they lay, or cutting them a little shorter to various heights - 8 to 24 inches.

What do I do in the spring?

Leave the remaining leaves in place. Assuming you didn’t add two feet of leaves, plants will grow through them and soon hide the remainder. The leaves will provide a natural mulch. Stems can be chopped and dropped in late spring - insects can work their way out of the cut stems too if left in place.

I have thick oak leaves - they take much longer to break down. Should I rake and bag these up?

No, you are actually very fortunate to have a native oak. Oak trees create leaf litter that sustains decomposer populations better than all other tree species. They provide ideal leaf litter for up to three years. Decomposers need consistent conditions to survive.

In a nutshell, leaving the leaves will save you time, effort, and money and help create a better soil, provide habitat for beneficial insects, and decreased runoff.

If someone asks you why you left the leaves - tell them “I’m doing it for the pollinators”.