With earlier springs and warmer fall days, pollinators need plants that provide resources at the farthest fringes of the growing season.
It’s long been a primary tenet of gardening for pollinators to ensure you provide plants that bloom throughout the entire growing season. Not only is this just good gardening, ensuring your landscape is colorful from spring through fall, as the two examples that follow illustrate, it’s more essential than ever to ensure your garden is prepared for pollinators not just during the peak of summer, but during the earliest days of spring and the last days of fall.
A recently published study looked at 40 years of climate and flower data in one region of Colorado’s Rocky Mountains. This long-term data set suggests that snow may be melting earlier than usual, lengthening the flowering season. While this initially sounds like good news for bees and other pollinators, the data also suggest that this is leading to an increase in long periods where flower counts are lower than normal. As spring ephemerals burst into bloom, they may complete their blooming period long before summer perennials have caught up, or may be nipped by a late frost, cutting off a supply of pollen and nectar early. Bumble bees, coaxed out of their winter slumber by a raft of warm days may go searching for flowers only to be caught out in the cold with nothing to eat.
On the other end, an unusually warm October and strong winds this fall have left many monarchs stranded in their northernmost range. Not only will these monarchs need late blooming sources of nectar to maintain their strength until they are able to fly south, they may not be able to find enough late-season food sources along their migration route to fuel their flight back to Mexico.
As gardeners, we can take extra steps to build resiliency for these animals as they face wild seasonal variations from year to year by seeking out those plants that bloom at the far fringes of the growing season and including them in our landscapes in ample numbers. In our book Attracting Native Pollinators, we suggest:
“To provide a continuous food supply, choose at least three different pollinator plants within each of the three blooming periods: spring, summer, and fall. Under this plan at least nine blooming plants should be established in pollinator enhancement sites; more is even better.”
Read on for some suggestions for either end of the blooming season.
We often look forward to tulips and daffodils as the first signs of spring. While these bulbs are a welcome bit of color in the otherwise green, brown, and grey landscape, they don’t provide a tremendous amount of resources for pollinators. Other spring bulbs, such as winter aconite (Eranthis hyemalis) and crocus may be less showy, but their open form and especially early bloom may make them amongst the first food sources available for spring pollinators.
This male carpenter bee isn’t going to go far from this crocus. It’s providing much needed pollen and nectar, and may attract a female for mating with. Photo: Justin Wheeler
While many native perennials should be reliably in bloom by May, native trees and shrubs such as pussy willow(Salix discolor) and spicebush (Lindera benzoin) as well as many fruit trees are often the first available sources of pollen and nectar for bees, budding out in March or April in most areas. Both spicebush and pussy willow are also host plants for many showy and attractive butterflies and moths.
May brings forth many spring ephemerals and wildflowers that tide pollinators over until the buffet of summer. There are many to suggest; consult our plant lists to find those that are recommended in your area.
Lest you not otherwise be able to tell, you know its fall when we enter the “Mum Madness” season, with mums popping up in grocery stores, roadside stands, and nurseries from coast to coast. While mums may be a feast for the eyes, they aren’t doing much of anything to feed pollinators at a time when they need a diet rich in protein and carbohydrates to sustain them as they migrate or head into hibernation.
A nice compliment to the rust colored hues of ornamental mums are the vivid yellows of goldenrod and deep blues and purples of asters. While many shy away from goldenrod due to its reputation for causing hay fever (which is fake news), or its notoriety as a garden “bully,” there are more than 100 species of goldenrod native to North America, and many more in cultivation that can fit most any landscape. Goldenrod is a monarch magnet, and provides much needed pollen and nectar late into the season.
This field of goldenrod is a welcome respite for monarchs, fueling their flight as they make their way south for the winter. Photo: Justin Wheeler
Another family of “late-bloomers” are asters. Though Chinese asters are often sold alongside those aforementioned mums, we’re talking about native asters, now known as the much more difficult to pronounce Symphyotrichum species (though many garden catalogs still stubbornly list them as Aster). Like goldenrod, there are scores of species of aster—some 180—native to North America, with a staggering diversity of colors, habits, and conditions in which they like to grow. Shady? Wet? Dry? There’s an aster for that! When selecting asters for your landscape, seek out those that are especially late-blooming, such as aromatic aster (Symphyotrichum oblongifolium), which I have observed blooming well into the depths of November in my zone 6 garden.
A bumble bee enjoying aromatic aster (Symphyotrichum oblongifolium) – one of the latest blooming native asters. Photo: Justin Wheeler
Though the fall colors or spring blossoms may be dazzling, take note as you visit gardens or arboretums, or go for hikes in natural areas during the early and late days of the spring and fall to see what’s in bloom. Invite these plants into your garden and you’ll be helping to provide emergency rations to help pollinators survive the boom and bust of our increasingly unreliable climate.