As your landscapes finish their fall decline, formerly lush and colorful plantings begin to turn into a collage of browns, blacks, and faded greens. The natural inclination may be to trim these areas back to the ground, especially stems with large and pendulous seed heads on them.
Although trimming the dead out of plants in the fall is generally good gardening practice for shrubs and trees, try to leave the seed heads on your more herbaceous plants this year. Seed heads left on plants over the winter offer a wide range of bonuses to the wildlife in your area, including giving hungry local birds a reliable buffet during hard times.
This goes for our native bees and other beneficial insects as well. The vast majority of insects are tucked away in the landscape during winter, either in their pupal forms or in a hybernative-like state called diapause.
Despite this, some North American bees and other beneficial insects are able to venture out into the landscape in winter during warm spells, and seed heads offer excellent protection for these creatures if they find themselves face-to-face with any hungry predators during their journeys.
By leaving the seed heads on your plants over the winter, you are of course also leaving most of the plant standing as well. Your beds will generally turn into huddled masses over the winter – encourage large wildflowers to fall off the beaten path by giving them a shove in the right direction, tucking them behind other plants if necessary.
Bumble bee queens tend to establish their small, 50-100 member colonies at the base of dense grasses, shrubs, or wildflowers in early spring. Try to let the base of stemmy plants like aster, echinacea, goldenrod and bee balm establish a dense collection of new and old stems to encourage your neighborhood bumbles to settle down in your garden. New queens also prefer to spend the winter in piles of leaves or other similarly insulated areas, so it’s important to have such a space nearby as well.
Don’t worry if you stumble upon a bumble bee nest or queen while cleaning up in the spring – just leave the area for a few minutes to let them get their bearings back, and continue your work in the area closer to sunrise or sunset if possible.
I like to cut the seed heads off of my plants in mid to late spring, leaving at least a foot of stem standing. You can toss any remaining seeds onto the ground to keep them available for hungry birds. For plants with large seed collections like goldenrod that you’d like to see in a certain space, simply bury the entire seed head a few inches under the soil.
The stems of most plants, especially those with pithy, semi-hollow stems, are also valuable to bees and other animals. Many of our wood nesting solitary native bees, which make up about 30 percent of the 4,000 or so known North American bee species, can nest in hollow stems of appropriate depth and diameter. They are able to enter a stem through natural breaks and can even make or enlarge holes of their own if they have to. Plants like river cane, raspberry, and joe pye weed are particular bee favorites.
Leaving your stems along with seed heads gives these animals some excellent real estate close to your garden, which can then benefit from the incredible pollination capabilities of mason bees, leafcutter bees and other stem-nesting powerhouses. As an added bonus, many of the same plants that tend to leave tall, lanky seed heads appreciate a shoulder to lean on as they grow in the form of last year’s skeletons.
Brannen Basham and his wife, Jill Jacobs, operate Spriggly’s Beescaping, a business dedicated to the preservation of pollinators. He can be reached at brannen.basham@gmail.com.
