by Carol F. Stoel
Forest Hills gardens are extensive and rich with flowering plants and trees that attract bees, birds and butterflies. Shouldn’t that be enough to support pollinators for the new rooftop vegetable garden atop UDC’s Building 44?
UDC’s experts didn’t think so. A pollinator garden was essential to enhance garden productivity, they said. Sandy Farber, the green roof manager and coordinator of the UDC Master Gardener program, designed the garden to attract bees and butterflies needed to collect and spread pollen. And Master Gardener volunteers installed the raised beds and irrigation in the southwest corner of the rooftop.
Sandy Farber. (photo provided by Farber)
Dr. Lorraine Clarke, a project specialist in urban agriculture and instructor at UDC, helps manage the garden. She gave me a tour of the beautiful facility and explained in detail later, via email.
Lorraine Clarke (photo by the author)
How do the bees find the rooftop garden? The short answer is, bees have “routes” that they establish.
“Colonies will send out scouts to seek out food,” Clarke wrote. “Once they find a large store of nectar (like our pollinator garden), they sip some nectar and go back to their colonies.”
A bee finds UDC’s rooftop garden. (photo by Sandy Farber)
“There is a cute little dance they do that actually communicates to other bees where the source of nectar is,” Clarke said.” (Check it out here.) “As more bees go to the source of the nectar, they keep coming back and communicating where the source is. Soon, an established route from that hive is created. Once things started flowering, there were a few bees and then suddenly there were hundreds! That speaks to the establishment of reliable nectar sources here.”
Many of these bees likely “belong” to DC beekeepers, Clarke said, which is good for people making honey here in DC. “Additionally, healthy native and kept hives means more pollinators and better pollination of fruits.”
“Tomatoes, cucumbers and peppers are all ‘pollinator dependent’ in order to create fruit,” Clarke said.
Tomatoes on the roof. (photo by the author)
“That means a bee or other pollinator must transfer pollen from one flower to another in order to trigger the formation of a fruit with viable seeds. More pollinators means more fruits! We did get some bees that came to our cucumbers when they first started up, but the establishment of the pollinator garden really jump-started the reliable fruit production at UDC.”
Other pollinators, such butterflies, are vital to a healthy urban ecosystem. So are plants native to the area.
Photo by Sandy Farber.
Bees can “learn” to get nectar from other plants with showy blooms, Clark said, but bees tend to gravitate towards native plants because their flowers and markings are familiar and the insects know they can rely on them for nectar.
The garden, supported by a small grant from Bayer Crop Science Corporation, is filled a variety of native plants that attract bees and butterflies.
1. Threadleaf Coreopsis (Native to North America, including DC)
2. Rosemallow (SE United States)
3. White Wild Indigo (Native to DC)
4. Purple Coneflower (Echinacea, Native to DC/Maryland)
5. Swamp Milkweed (Native to DC)
6. Purple Gayfeather (Native to DC/Maryland)
7. Golden Fleece (Native to Southern U.S., not D.C.)
8. Black Eyed Susan (Maryland State Flower!)
9. Variegated English Lavender (Native to Europe, only non-native)
10. Joe Pye Weed (Native to DC/Maryland)
Most of these will survive the winter.
Clarke says at least three different kinds of bees have been spotted in the garden – the tiny native and European honeybees (they are hard to tell apart), the big brown bumblebee, and occasionally the huge black/brown carpenter bees. They also regularly get checker spot butterflies, some swallowtails, and the occasional monarch (they like the milkweed). Hummingbirds also visit.
Photo by Sandy Farber.
The gardens are directly linked to the Master Gardeners program. Master Gardeners have to put in 50 hours of volunteer time in the gardens to get their certificates. As a result, the gardens get great care, and the students learn about the latest research being conducted in the garden as well as participate in important discussions and decisions about next steps in developing the gardens.
Photo by Sandy Farber.
Pollinator experts noted above include Sandy Farber, UDC CAUSES Dean Sabine O’Hara, Associate Dean for Land-Grant Programs William Hare, and Dr. Dwane Jones, director of the Center for Sustainability Development.