By Martha Keehner Engelke, NC State Extension Master Gardener SM volunteer of Durham County
Winter is the perfect time to make a plan to revise your garden. For many, that means making your garden more attractive to pollinators. Recently, I learned that building a garden that makes the A-list for pollinators is not just about the plants. I had an opportunity to interview Dr. Danesha Seth Carley, PhD Associate Professor in Horticultural Science at North Carolina State University (NCSU).
Dr. Carley’s expertise is sustainable management of urban landscapes with a focus on pollinator ecology. Her recent research programs include pollen quality in commonly planted wild-flowers, pollinator ecology, and pollinator habitat establishment. She has conducted her research along North Carolina roadways and at the historic Pinehurst #2 and #4 golf courses.
I heard Dr. Carley speak at a program sponsored by the Gardening Association of North Carolina . I contacted her, and she graciously agreed to a follow-up interview. She expanded on topics discussed in her presentation as well as her book Pollinator Gardening for the South: Creating Sustainable Habitats (co-authored with Anne M. Spafford)1.
Butterflies, bees, flies, wasps and birds are all considered to be pollinators. The most important pollinator is the bee. Bees contribute millions of dollars to the U.S. economy through pollination. (Images credit: Pixaby)
What does a pollinator want?
Let’s talk about the most important pollinator: Bees. There are two main categories of bees: social and solitary. Social bees are divided into 3 categories: bumblebees, honey bees and stingless bees (which are not well understood). Solitary bees, which are a larger category, include carpenter bees and the tiny sweat bee. In her book, Dr Carley tells the fascinating story about the social life of bees (as well as other pollinators).
The gardener needs to remember that pollinators choose plants that are best suited to their anatomy particularly tongue length (proboscis) and mouth parts. Bees are attracted to bowl-shaped flower that often have a prolific pollen ring in the middle. Native bees enjoy feasting on plants in the Asteraceae, Salix, Solidago, Helianthus, and Symphyotricum families. Butterflies and hummingbirds have longer tongues. They will be attracted to more tubular flowers such as Fuchsia (Fuchsia spp) ; Bleeding heart (Lamprocapnos spectabilis); and Turk’s cap lily (Lilium superbun).
All varieties of a particular plant are not equal when it comes to pollinators. Cultivars are often bred to maximize flower size, disease resistance, or aroma. This means that the cultivar may have less quality pollen than the plant from which it was bred. If you see the plant described as “flora pleno” (meaning with a full flower) it is likely to be a double bloom and thus less accessible to pollinators. A plant that is considered to be a great pollinator as a single, loses some of its attraction when it is a double. For example, Purple coneflower (echinacea purpurea) is one of the best plants for a pollinator garden but a number of cultivars with double flowers are more difficult for pollinators to access.
On the left echinacea purpurea has single flowers and is considered to be a great flower for pollinators. One the right, the flowers of Echinacea Supreme™ Elegance make it more difficult for pollinators to access. To some gardeners, the cultivar may seem more beautiful but the pollinators don’t see it that way. (Image credit: NC Tool Box; National Gardening Association, NJ Bob)
Someone like Dr. Carley is frequently asked which plants are the best for pollinators and she has an answer for her “Big Five” plants. They are: Mountain Mints (pycnanthemum sp.); Coneflowers (Echinacea purpurea); Butterfly Milkweed (Asclepias tuberosa); Asters (Symphyotrichum sp); and Blanket Flower (Gaillardia pulchella).
Pollinators are attracted by pollen and nectar. Desirable pollinator plants include: Mountain Mints (Image credit: ( NC Extension, Kerry Woods CC BY NC); Coneflowers (Image credit: NC Extension, Cathy DeWitt, CC BY 4.0) ; Butterfly Milkweed (Image credit: NC Extension, Mary Keim CC-BY-NC- SA-2); ; Asters (Image credit: NC Extension Douglas Goldman, USDA CC BY 4.0) ); and Blanket Flower (Image credit: elephantkitty CC BY NC ND 2.0)
The Importance of Structure/Composition
Just like humans, pollinators need two things to survive: nutrients (carbohydrates from nectar, protein from pollen) and a safe place to live and work. To be on the “A-list” pollinators want access to high quality pollen and nectar and protection from predators. This is why the structure of a garden is important.
Many of us approach gardening from the perspective of “buy one, plant one”. In our quest to have a lot of different plants, we may be reducing the attraction of our garden to pollinators. Planting clumps of plants rather than a single plant can help pollinators be more efficient. For example, honey bees and bumble bees enjoy goldenrod (Solidago). If you plant one goldenrod the female bees (the males don’t forage) collect the pollen on their hairy bodies (which is one reason they are the best pollinators), and then transfer it to their rear legs into their “pollen basket”. They mix the pollen with a bit of nectar to hold it in place and head back to the hive. If she has to do this several times because one plant doesn’t provide enough pollen, she is less efficient and it means that she might have less energy and be more susceptible to disease. There are two ways to prevent this: plant clumps of good quality plants or increase the diversity of your plantings (next section).
Goldenrod (Soldaigo spp. is a great plant for pollinators including this honey bee. When planted in clumps it helps the bees (and other pollinators) be more efficient. Of course, Goldenrod is a fast growing plant so you don’t need too many of them. (Image credit: NC Extension Plant Tool Box, Hope Duckworth)
Space for a happy home and safety from predators and toxins are other considerations related to the structure of a pollinator garden. While social bees (like honeybees) will live happily in wooden boxes or hollow trees, solitary bees dig their nests in the ground or in tubular stems. Resisting the urge to cut plants with hollow stems until the spring temperature is above 57oF (the temperature when bees become active) allows bees to have a safe home for the winter.
It is also important to plant your pollinator garden away from areas that will be treated with pesticides and away from public walkways. Some people are allergic to or afraid of bees or consider flies and wasps to be a nuisance. If your garden is in the front of your house, you might want to plant your best pollinating plants toward the back of the bed. A strategically placed shrub or tree is another way of protecting pollinators.
A cluster of orange coneflowers allows butterflies and birds access to abundant nectar and seeds without excessive movement or exposure to predators. The shrub in the back offers protection. (Image credit: NC State Extension, Chris Moorman)
Diversity/Seasonality
A garden made of different types of plants (especially if they are native) is the best type of pollinator garden. Native plants are best because pollinators and native plants have evolved together. The NC Wildflower Association has developed an excellent chart of native plants that includes sun requirements and seasonality. The NC State Extension office provides a list of pollinator plants that include trees, shrubs and vines. These are useful tools in developing a garden that will valued by pollinators all year round.
As you begin your landscape design, be sure to think vertically as well as horizontally. Dr. Carley cautions that you need layers for depth and smooth transitions between plant layers. Thin clumps (or sweeps) of perennials that bloom early in the season that are planted close to other perennials that bloom later means that you have diversity as well as seasonality. It also makes your garden look better because something is always blooming.
To get some height consider a tree. One of the best is the Eastern Redbud (Cercis canadensis). It is one of the few plants that has flowers before leaves. It blooms in early spring when pollen from other plants is scarce and it has high quality pollen and nectar. Honey bees, bumble bees, mason bees, cuckoo bees, long-horned bees, mining bees, and sweat bees love it. Redbuds are also a host plant for the larvae of several butterflies and moths. Songbirds and some other mammals eat the seeds. What’s not to like?
Pair the Redbud with shorter shrubs such as a native Sweetbush (Clethra alnifolia) which blooms much later but is visited by hummingbirds, butterflies, native bees, and later by birds who enjoy the fruit and a few shorter plants like the Cardinal Flower (Lobelia sp). Maybe even a few annuals for filling those bare spaces? Now you have a garden that is on the A-List for pollinators but is also attractive to look at.
Eastern redbud (top left) is one of the first plants to flower in the spring, and cardinal flower (right) and goldenrod (bottom left) are two excellent late-season nectar sources for bees, butterflies and other insects. (Image credit: NC Cooperative Extension, left photo by Alice B. Russell; other photos by Chris Moorman)
As a final thought, I quote Dr. Carley “there is no garden too small or landscape too large to include pollinator habitat. Together we can help protect our pollinator friends, and maybe we can inspire others along the way”.1
Note1: If you are interested in getting Dr Carley’s book, it is available through UNC Press.
Additional Reading and Resources
To learn how you can foster a home for bees during the winter consider leaving these plants with pithy stems during the winter. If you need to cut them, leave the long stems until spring in an obscure place in your landscape: https://content.ces.ncsu.edu/how-to-manage-a-successful-bee-hotel/appendix-3-plants-that-produce-hollow-or-pithy-twigs-and-stems-used-by-nesting-bees
Here are some suggestions on specific plant that will attract pollinators to your garden:
https://content.ces.ncsu.edu/landscaping-for-wildlife-with-native-plants
The North Carolina Arboretum provides suggestions for plants and landscaping for a home pollinator garden: https://www.ncarboretum.org/2020/05/08/ask-the-arboretum-creating-a-pollinator-paradise-garden/
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