September and October are particularly crucial for the survival of bumblebees and smaller native bees. It’s the time of year when they are mating and taking in their last bit of nutrition before going through diapause (similar to hibernation) in the case of bumblebees, or lay their last set of eggs in the case of native ground bees such as mining and leafcutter bees. Honeybees, syrphid flies and monarch butterflies are also busy getting the last sips of nectar during these early fall months.
Gardeners can help by planting a few important perennials that flower in the fall. Here are some that you can see for yourself at the Penn State Master Gardener Pollinator Garden in Fairmount Park. Free and open to the public, the garden is adjacent to the Horticulture Center, near Belmont and Montgomery avenues.
It’s not true that goldenrod causes fall allergies — the pollen is not wind-blown and goldenrod is are dependent on bees for pollination. Tall goldenrod (Solidago canadensis) grows 6-8 feet tall while prairie goldenrod (Solidago nemoralis)is only 2 feet tall.
Golden fleece (Solidago sphacelata) is a very short goldenrod that is a favorite of the tiny mining bees. It has an intriguing corkscrew spike out of which the tiny flowers grow. This is a non-aggressive goldenrod and does not easily self-sow. Its basal leaves persist through the winter. It’s important not to let the plant get smothered by a pile of fall leaves.
The New England aster (Symphyotrichum novae-angliae) has pink/purple blooms and is very well loved by bumblebees, Monarchs and syrphid flies. New England asters can be cut back in mid June to about a foot to keep the plant more compact. Some cut it back a second time between July 7 and 14 but no later as that will interfere with flowering.
Aster oblongifolius “Raydon’s Favorite” blooms in October also attracts bumblebees and migrating monarchs. It pairs well with the golden foliage of bluestar (Amsonia hubrechtii). There’s no need to cut back Raydon’s Favorite, but it may need staking.
Interestingly, goldenrods are in the Asteraceae family, same as asters and all daisy-like flowers (think coneflowers, black eyed Susans, sunflowers, zinnias, marigolds) since they have ray petals surrounding a disk of tiny flower parts in the center of the flower.
This member of the mint family (Physostegia virginica) is so-called because when the flowers are pushed to the side, they remain in that position. The light purple bell-shaped blooms can continue into November and are well liked by large bees such as carpenter bees. This plant needs no special care at all.
New York Ironweed
Ironweed (Vernonia novebroacensis) can grow to 8 feet tall and has small purple blossoms that are excellent nectar sources for native bees. It self-sows but seedlings are easy to identify by their finely serrated leaf margins. At the Pollinator Garden, we stake this plant to keep it from toppling in late summer storms. If you prefer a shorter blue flower in the fall, try blue boneset, a/k/a blue mistflower (Conoclinum coelestinum), another perennial in the aster family. It remains short until late summer when it sends up foot-tall stems with lovely fuzzy blue flowers. Butterflies love this plant.
For me, one of the best aspects of native plants is that once they are established, they do not need any watering and require minimal care. At the Pollinator Garden, we do not cut down any perennials until late March or very early April when we are getting ready for spring. The spent stems provide cover for overwintering insects, food for birds and winter protection for the crowns of the perennials.
Come visit this garden in September and October to witness some of the splendors of fall in Philadelphia.
Howard Goldstein is a Weavers Way Working Member.