It’s that time again—National Pollinator Week—when we pay a little more attention to the hard-working animals who give so much. They help pollinate about 75% of flowering plants and nearly the same amount of our food crops. Without them, life would be very different. So let’s honor these fascinating creatures who face seemingly insurmountable threats, including habitat loss, climate change, and pesticide use. It’s tragic and overwhelming, but there is much that each of us can do as individuals, and together we can have a tremendous influence over potential habitat in everything from tiny urban lots to community gardens to large rural expanses.
Even a small garden can make a difference. For example, in my Pacific Northwest yard I offer a variety of native flowering trees, shrubs and perennials throughout, as well as a mini-meadow where locally native perennials—such as columbine, fleabane, checker mallow, blue-eyed grass and iris—grow and buzz with life. Equally important is leaving leaf “litter” and dead wood around, and not doing any “clean up” until well into spring, so as to not disturb overwintering adults, eggs, larvae, or pupa, camouflaged so well. For example, the strikingly beautiful western tiger swallowtail butterfly may overwinter as chrysalis (pupa), which looks like a little piece of wood during that time. Other things we can do for pollinators include participating in “citizen science” projects that seek input from gardeners, and advocating for an end to pesticide use in our parks and communities.
At home, here are ten things we can do to attract and support a variety of pollinators, from bees and butterflies to beetles and flies.
Grow a variety of plants that are native to your area, and you won’t need to think too much about whether you will provide food for pollinators. Research suggests that native plants are four times more alluring to native bees, for example, than exotic flowers.
Got lawn? Whether you have a large or small lot, consider replacing or minimizing turf with native grasses and wildflowers, or perennials and mosses in shady areas. Add shrubs and trees to provide cover and protection, especially for bees who create nests in the ground.
Leave parts of your garden a little “wild.” Undisturbed nesting locations are absolutely essential, and gardens that aren’t too neat and provide log piles, mounds of rounded stones, exfoliating tree bark, and patches of bare, well-drained, undisturbed soil will help. From fall till spring, allow leaves to remain undisturbed on the ground so that overwintering butterfly and moth eggs/caterpillars and bees can slumber peacefully under a leafy ceiling. For the numerous species of ground-nesting bees (70% of bees nest in the ground, like ants do), avoid extensive tilling or anything that prevents access to soil, like plastic mulch or thick layers of organic mulch. Nest sites for bees that nest aboveground can be supplemented by horizontally placing hollow or pithy stems, or blocks of wood or downed wood with dead-ended, narrow holes drilled into them. Some species also utilize the vegetative parts of plants for food as well as cover or resources for nesting.
Steer clear of pesticides. Even those approved for organic gardening, such as rotenone, are harmful. Systemic insecticides like neonicotinoids (a class of insecticides such as imidacloprid, acetamiprid, clothianidin, dinotefuran, nithiazine, thiacloprid and thiamethoxam that affect insects’ central nervous systems), are absorbed by plants and produce toxic nectar and pollen. Studies show that residues may persist in woody plants for up to six years following application and may persist in soil for several years. Herbicides and fungicides can also be harmful. In a healthy, balanced system there should be no need to resort to poisons.
Turn roadsides native. Studies show that native pollinators are much more prevalent in native stretches of roadside habitat—often the only connection between patches of remnant habitat—than weedy, nonnative stretches. If you own rural land, plant natives near your roadside and mow it infrequently to prolong bloom and prevent harm to creatures who may be taking cover within it.
Provide nectar and pollen in variety of flower color, shape, and size for pollinators with different needs. Flower nectar, produced in glandular organs called nectaries, is high in carbs and serves to attract pollinators to distribute plants’ pollen (and in some cases, attracts protectors like parasitoids and ants—which also pollinate to a small extent—against herbivores that may be problematic). Pollen is a highly nutritious blend of proteins, lipids and carbohydrates. We’ve been taught that bees tend to prefer yellow, purple, and blue flowers—anything but red, which they can’t see—while hummingbirds can see and do use reds (although one study suggests that their preference may not be innate, but rather they choose them since bees don’t). While this is true, a 2016 research study shows that bumblebees (and probably other pollinators) choose a plant for the nutritional quality of its pollen, not only its color; they were found to need pollen with a high protein to lipid ratio (which makes sense, since the pollen is mainly used to feed their growing larvae). And new research out of UC-Davis suggests that pollinators choose among flowers based on the microbes within those flowers, such as yeasts that are”commonly found in flower nectar and … thought to hitch a ride on pollinators to travel from one flower to the next. Its scent production may help it attract pollinators, which then help the yeast disperse among flowers.” But flower shape and size also matter: butterflies need clusters of short, tubular flowers with a wide landing pad, such as yarrow (Achellia millefolium occidentalis), various native bees need different types of flowers (generally shallow), while hummingbirds like relatively large, tubular, or urn-shaped flowers.
Keep it blooming. From spring through fall, something should always be in bloom, preferably several species at a time. In the Pacific Northwest, early spring flowers, like those of Indian plum (Oemleria cerasiformis), willows (Salix), and red-flowering currant (Ribes sanguineum), are particularly important to bees emerging from hibernation, while late-season nectar sources such as asters (Symphyotrichum spp. or Aster spp.) help bees that overwinter as adults get through the winter. Both early and late forage may aid in bees’ reproduction. Of course, mid-summer flowers are important, too! Many native species bloom for extended periods, such as charming foamflower (Tiarella trifoliata), which may produce flowers from spring to late summer. Learn when plants bloom to be sure you’ve got it covered, and aim for some overlap in bloom times. Remember that trees and shrubs, as well as perennials and annuals, can provide nectar and pollen. Arrange plants in clusters or drifts or swaths of at least three different plant species so that each plant is next to or within a few feet of another of its kind, to supply enough forage and to make them easy for pollinators to find.
Moisten sand or loose soil to help adult butterflies. Butterflies and moths ingest liquids like flower nectar from which they obtain sugars, minerals, and other nutrients. But they also need to “sip” from muddy or sandy puddles, sap, decaying fruit, sweaty humans, even manure piles to hydrate themselves and obtain dissolved minerals, including salt. Such minerals are vital for many physiological functions, including reproduction: Males often transfer “nuptial gifts” of sodium and amino acids to the female during mating (along with other donations). Before you say, “He shouldn’t have,” consider how evolution toward generosity might generate rewards: more gifts mean more nutrition and better egg survival. To assist, add a dash of salt to containers of moist sand or soil, to be sure they get what they need.
Grow butterfly host plants. To become adults, butterflies in earlier life stages—egg, larva, chrysalis—require host plants that provide habitat and food. Find out which butterflies frequent your area, and grow the plants that provide for all their stages. In the Northwest check out these handy guides: Create a Butterfly Garden (OSU) and Butterflies and How to Attract Them (WDFW).
Forgo hybridized and “double” flowers. When choosing nonnative plants, keep in mind that hybridized varieties may lack sufficient pollen nutrition—pollens vary in protein content, and bees and other pollen consuming insects need a wide variety to fulfill their protein requirement. Research also suggests that some commonly used garden plants, especially those hybridized for features valued by gardeners, like disease-resistance or flower size or color, may not provide sufficient or appropriate nutrients in nectar, needed for carbohydrates. Frilly double-flowered varieties (those with extra petals that make a flower look inflated and flouncy) are usually inaccessible to pollinators simply because they can’t get through the mass of petals to the nectaries. It’s a bit sad to watch a bumblebee, trying but unable to get inside an overly dressed flower, fly away without food.
Adapted from content originally published in my book, Real Gardens Grow Natives: Design, Plant, & Enjoy a Healthy Northwest Garden.