Master Gardener: Leave Garden Debris Alone To Help Insects In Winter

Brian Jervis Ask a master gardener

"I've seen quite a bit of information on social media suggesting not cleaning our gardens in the fall and instead waiting until spring to help the bugs. How will this help the bugs?" -Kyu

There has been a lot of talk in recent years about leaving plant debris in place until spring to help insects overwinter. This advice challenges many gardeners, whose last job outdoors is usually to remove all dead stems from garden waste. But there are good reasons to leave it alone until spring.

Monarch butterfly migration is familiar to many of us, but this migratory behavior is the exception rather than the norm in the insect world, as that is where most insects overwinter.

For example, butterflies and moths such as grouse, moon moths, and sailfish overwinter in pupae and mix with dead garden leaves and stems. Fireflies and native bees (including bumblebees) like to hide in fallen leaves or even dig a few inches under the leaves to find a good home until spring. Some bees find the hollow stems of dead plants an ideal place to overwinter.

By leaving your brown flowering plants until spring, you can also get seed pods that can be eaten by a variety of birds such as goldfinches, woodcreepers, tits, cardinals, and sparrows.

So, to encourage these natural habitats and food sources, the first thing you need to do is delay this urge to clean up the garden until we have a few days in spring that get over 50 degrees. Flower stems that have seen better days don't need to be cut and discarded. And you don't have to rake all the leaves out of your flower garden by spring.

Leaving the leaves in your garden for the winter not only makes them a home for overwintering insects, but also helps conserve moisture for your plants. As they decompose in winter, they decompose and return more organic matter and essential nutrients to the soil.

If you want to do your best to encourage the insects to overwinter, you can leave the leaves on your lawn over the winter. However, it will be harder to sell to those who are proud of their lawn. As a compromise, maybe leave the leaves in your flower garden by mowing them across the lawn with a mulching mower. This will help bring nutrients and organic matter back into the soil, and who doesn't love that? Lots of luck.

You can get all your gardening questions answered by calling the Tulsa Master Gardeners Helpline at 918-746-3701, stopping by our Diagnostic Center at 4116 E. 15th St., or emailing us at mg@tulsamastergardeners .org.