Ecologically sensitive fall garden maintenance

By Bonnie Kirn Donahue

Editor’s note: By Bonnie Kirn Donahue is a UVM Extension master gardener.

It’s September, and to many gardeners, that means it’s time for end-of-the-year garden maintenance. This includes cutting back plants, clearing out leaves and composting most of the vegetation that grew this season.

Before continuing the normal routine, it’s a good time to step back and think about the bigger picture. A question to consider is why do we clear out our gardens before the winter? What’s the purpose?

One of the reasons that we put our gardens to bed is that herbaceous plants (like annuals and many perennials) will not hold up through the winter. Foliage turns brown and crispy, and the moisture from snow breaks down leaf structure.

Perennials store energy in their underground root systems and regrow fresh vegetation in the spring. Annuals are just that, and need to be replanted in the spring. The foliage of both is often cut back before the next growing season.

Additionally, cutting back certain foliage in the spring can be a wet, gooey mess, and it is often easier to cut back plants when the soil and plants are dry.

A final reason for cleaning up garden foliage is to eliminate those diseases and pests that may overwinter on the dead plants or in the soil. Since pests and diseases can build up if plants are grown in the same place every year, make notes or a map of where your crops were in the garden this year and rotate them to a new spot next growing season.

I suspect that another reason for fall garden maintenance is the desire to have a tidy-looking garden at the end of the season. This is an opportunity to look at the bigger picture, and change our thinking.

In this case, appearance and ecological function are at odds. Many beneficial insects and caterpillars overwinter as eggs, larvae or adults in leaf litter. Bees and other beneficial insects create homes in hollow plant stems until spring. Birds feast on seeds to survive the long winter.

Take a look at a natural area near where you live, and think about how it changes through the seasons. Nature is not tidy or clean. It is beautifully messy, regenerative and evolving.

If we can adjust our expectations about what is beautiful, and follow the lead of nature, we can cultivate gardens that are both lovely and ecologically sensitive.

How can we do this? Start by leaving the plants with seed heads up through the winter. See which plants withstand snow loads, and which plants birds visit. Use this to decide what to do next year.

In my garden, plants such as sunflowers (Helianthus spp.), purple coneflowers (Echinacea purpurea) and black-eyed Susan (Rudbeckia spp.) hold up to the snow.

Leave plants with pithy, hollow stems such as milkweed, asters, goldenrod, bee balm, raspberry, elderberry, rose, ornamental grasses and many wildflowers. These stems will provide beneficial insects, including butterflies and bees, with homes throughout the winter.

Don’t remove all the leaf litter in your garden. This natural blanket not only provides food sources and a home for butterflies and moths during cold months, it also provides nutrients to the soil as it breaks down.

Ideally, a layer of leaf litter could be left in your garden forever.

But if you need to remove it, wait until after the insects have had a chance to emerge and relocate in late spring.

While many of the traditional fall-maintenance practices are valid, they are not applicable in allcases. Essentially, garden maintenance should be performed on a plant-by-plant basis.