Habitat at Home: Seed Heads and Bee Habitats
As fall marches on toward winter, and vegetation prepares its end of the year life cycle, we’d like to update a previous Habitat at Home article on what to do with seed heads that are left over the winter. Let’s focus on allowing them to be used for nesting bees. What can you do in your yard to create sorely-needed bee habitats?
We emailed with Brannen and Jill with Spriggly’s Beescaping, which provides educational workshops, exhibits, and services for pollinators, conservation efforts, and nature in general. They said the seed heads themselves don’t offer anything in the way of forage for bees over the winter–although they do provide a valuable food source for birds. The vast majority of insects are tucked away in the landscape, either in their pupal forms or in a hibernation-like state called diapause.
“Despite this, some of our native bees and other beneficial insects are able to venture out into the landscape in winter, and seed heads offer excellent protection for these creatures if they find themselves face to face with any hungry predators during their journeys,” they said.
Depending on the plant, it’s beneficial to either leave the seed head intact over the winter, or to cut it down, making it easier for certain bees to enter and nest.
“By leaving the seed heads on your plants over the winter, you are of course also leaving the rest of the plant standing as well,” said Spriggly’s. Stemmy plants such as itea, echinacea, goldenrod, and bee balm can be left to establish a dense collection of new and old stems which will encourage neighborhood bumblebees to settle in your garden.
Leaving the stems and other above-ground growths of your plantings rather than cutting them down in the fall offers other wide-ranging benefits to the native bees and other beneficial insects looking for a place to find shelter and make their nests. Bumble bee queens tend to establish their small, 50-100 member colonies at the base of dense grasses, shrubs, or wildflowers.
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.
“I like to cut the seed heads off of my plants in early spring, leaving at least a foot of stem standing. You can toss any remaining seeds onto the ground to keep them available for birds,” they said.
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 North American bee species, can also nest in hollow stems of appropriate depth and diameter. They can enter a stem through natural breaks and can even make or enlarge holes of their own if they have to.
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. If your seeds are looking ratty in the spring, make sure to leave at least six inches of stem above ground after you cut them, preferably more if possible.
Fuzzy stems are also beneficial, as they will offer benefits to wildlife such as carder bees, who will strip the stem bare and use its fuzz in the construction of their nests. Although these bees are an introduced species in the area, they don’t seem to be aggressively displacing any of our native species yet, and still perform pollination services in and around your property.