Native Gardening with Jimmy: Winter leaves grow summer wings
By Jimmy Rogers
A few weeks ago, a dazzling butterfly perched gracefully atop one of my milkweed flowers. I followed the standard procedure for these situations: chase it all over the garden with my phone to take the perfect picture. I fed the image into Google Lens to determine which species had visited me. Upon learning it was a variegated fritillary, I realized that a long-term gardening project had finally come to fruition.
I caught the native gardening bug last year and designed several garden beds to replace my front lawn. The design depended on a living-mulch strategy, meaning I needed lots of low-growing plants to defend against invasive weeds. Searching the native gardening community, I discovered that almost everyone was willing to share native violets. They are leafy, stay quite short and produce purple flowers in the spring.
As I collected violets at plant shares and the home gardens of generous neighbors, I began to research what ecological value violets might have. I was surprised to learn they are the host plant for the fritillaries, which are a group of beautiful butterflies. And unlike other butterflies, you might never see their caterpillars.
Rather than laying their eggs on violet leaves, female fritillaries lay them in nearby leaf litter. In order to evade predators, the caterpillars wait until night to crawl out of their leafy homes and munch on violet leaves. Before day breaks, they’re back in hiding. This means that if you’re a hopeful butterfly farmer like me, violets are only a host plant if our gardens contain leaf litter.
Once I learned about the enigmatic life cycle of this otherwise showy butterfly, I added leaves to my garden design. Each autumn, I let leaves lie where they fall in my garden beds. If they land somewhere inconvenient (like, say, the sidewalk), I pick them up and put them between my plants. Turf-grass lawns can also benefit from a layer of leaves, as long as the tips of the grass are poking through to allow for gas exchange. Wherever you leave your leaves, you will be regenerating the topsoil and suppressing weeds. If you end up with more leaves than you can use, ask your neighbors who don’t have many trees (like me) if they would like some of yours.
As a child, I remember many seasons of passing our leaves through a vertical chipper and then bundling them in plastic yard waste bags. Now I know we were not only shipping away free mulch (in single-use plastic, no less), but we were literally shredding any of the insect life that had grown in our garden through the spring and summer, especially the eggs and caterpillars. If you’re gardening for wildlife, do what you can to preserve whole leaves in your garden beds, rather than chipping them or running over them with a lawn mower. And think: You won’t need to invest in more bark mulch every year, either.
One criticism I’ve seen of this approach is that the leaves will blow away in the first breeze. This depends a lot on your garden’s plant density. If plants are spread apart as much as a foot and surrounded with bark mulch, then leaves will likely escape. Closely-planted individuals will act more like a net, grabbing and holding the leaves until they can break down. If your garden is sparsely planted, fall is a great time to add native ground covers, which will help keep the leaves in place as soon as they fall.
While spreading those extra leaves, you may also appreciate your plants heading into winter dormancy. Many plants change colors or leave sculptural stems for winter interest. There is no need to clean up a standing stem, especially if it still holds seeds for hungry granivorous (seed-eating) birds. However, if you do need to cut spent foliage to manage your garden, consider leaving stems to 18 inches long (or even longer), so that stem-nesting bees can stash their eggs and bee bread, a mixture of pollen, nectar and bee saliva, there next summer. This year, I saw my first stem-nesting bee taking residence in one of last year’s beardtongue stems.
While on the topic of cleanup, I encourage you to consider the chop and drop method, which allows old stems and twigs to break down in the leaf litter. This saves us time we might otherwise spend bagging or tying stems for curbside pickup. If you have a lot of stems, consider making a brush pile, which can become home toground-nesting bees, lizards, birds and small mammals.
If butterflies and bees charismatically wing through pollinator gardens in the spring and summer, who comes to inhabit a winter garden covered with leaves? As you may have guessed already, almost all of the insects we love to see in summer finish their life cycles in our leaf litter (or underground). Fireflies and giant luna moths are particularly well known for their dependence on decaying leafy material.
This year in Laurel, the city’s Bee City sub-committee is encouraging all residents to leave the leaves. Not only can we save ourselves the chore of hauling leaves to the curb, we can renew the soil, suppress weeds and promote insect diversity right in our own gardens..