Cooler temperatures are finally here and with those cooler temperatures we have some decisions on the horizon to make. Historically, gardeners of both flowers and vegetables have cleaned up their gardens at the end of the season, removing all the dead plants, stalks, and leaves etc. But we are learning that, while this strategy may make our garden spaces look nice, we may unintentionally be doing damage to our local insect population. And with declining pollinator populations, we need to help them out as much as we can. So, here’s the deal.

Most of us are at least somewhat familiar with migration of monarch butterflies which might give us the impression that most insects migrate to warmer climates during the winter. However, this is not the case. Most insects tend to overwinter close to where they call home. And this overwintering occurs both underground and in plant debris. By debris I mean fallen leaves, twigs, and stalks from flowers that are done for the year.

Here’s a few examples of insects that endure the winters here with us. First of all, a variety of moths and butterflies such as luna moths, swallowtails, and fritillaries, overwinter during their chrysalis stage during the winter. These chrysalises are often difficult to see since they are designed to blend in with dormant vegetation, but they are there.

Fireflies and native bees (including bumble bees) like to overwinter in leaf litter or even in the soil a few inches beneath the surface. Some bees spend their winters in the hollow stems of dead plants. So, when we clean up and clear out our gardens, we are more than likely also throwing away a variety of insects attempting to overwinter in our landscape.

Some of you might be thinking, that’s great. That’s exactly why I clean out my garden, so I can help minimize insects and disease for next year. That makes perfect sense, except it’s pretty much impossible to remove the detrimental insects without also diminishing the beneficial insect population as well. Now here is where we could have a longer discussion about all insects mattering, but yes, all insects have a place in our ecosystem whether we consider them a nuisance or not. Except maybe squash bugs… So, what’s a gardener to do?

The first thing you can do is to postpone your garden clean up until spring. Yes, your landscape may not look pristine and well-tended during this time, but hey, leaving the garden to it’s own devices during the winter will free up some time in your fall for activities you might enjoy more, right? And let’s face it, if we’ve been out watering, weeding, and tending the garden since March, it’s ok to want a little break (I know I do) and let nature do what nature does best.

If that is you, here’s your permission to leave those brown stalks and leaves etc. in your garden until the spring…and there was much rejoicing. If any of your neighbors happens to say anything, just tell them you’re doing it for the pollinators. It’s hard to argue with that.

Leaving these brown flowering plants can also provide seed heads that will be food for a variety of birds such as nuthatches, goldfinches, chickadees, sparrows, and cardinals.

If you just can’t do it and won’t be able to sleep at night if you don’t clean up the garden, how about this as a compromise. Rather than cutting down the dead stalks and putting them in the trash, cut them down and put them all in a pile in the corner of the yard or someplace that works. This will give the overwintering insects a place to call home while still allowing you to give your garden a good clean up. Sounds like a win-win to me.

There is another benefit to leaving those leaves on the ground during the winter in that those leaves will act as a mulch during the cold weather. This will help retain moisture in the soil for your plants. In addition, as these leaves get broken down by the elements, they will be returning essential nutrients back to the soil as well as organic matter.

So, if you’ve made the commitment to leave the debris until spring, you’ll need to leave it alone until we have a few days of 50-degree weather in the spring. At this point the insects will begin waking up and coming out of dormancy. Then it will be safe to dispose of that debris in ways that work for you. Plus, aren’t we all a little more motivated to work in the garden in the spring? I know I am.

But here’s my exception to the no clean up rule in the garden…squash bugs. If you’ve had an issue with squash bugs (and you have if you’ve grown squash) they also overwinter in the soil. So, disrupting their life cycle by tilling up your garden soil in the fall and again in the spring, is just fine with me. My apologies to my no-till garden friends. We each have our own battles to fight. See you in the garden!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo of Luna Moth Chrysalis - Sturgis McKeever, Georgia Southern University, Bugwood.org