I wrote this for the Tiny Cottager magazine, with a particular focus on the sandy conditions in which cottagers garden. There are many more great pollinator plants than the 15 in the downloadable list at the end of this article! But they are a good start.
About 10 per cent of flowering plants are wind-pollinated but the overwhelming majority rely on insects for the process that results in fertilization, seed production and future generations. Bees are the essential pollinators, designed for the efficient transfer of pollen grains from one flower to another.
There are more than 400 species of native bees in Ontario. Of these, only the 16 species of bumble bees live together in colonies. The rest are solitary bees, the female nesting in sparsely vegetated soil, hollow stems, twigs or wood cavities. Not being territorial, solitary bees are unlikely or not equipped to sting.
The European honey bee was introduced and competes with native bees for floral resources. It can sting, but won’t unless provoked.
Recent research indicates that the pollination role of moths, with their hairy underbellies, has been underestimated. Most moths are nocturnal. Artificial light at night adversely affects all insect populations, but especially moths. Butterflies tend to be incidental pollinators, only lightly contacting pollen when they sip up nectar. There are exceptions – one, cited by Heather Holm in Pollinators of Native Plants
, is the Peck’s Skipper butterfly, the primary pollinator of Prairie Phlox.
Other pollinators are flies, beetles and wasps (the latter is docile while nectaring, aggressive if the nest is threatened. If an unwanted paper nest is being built, hang a fake nest nearby and the territorial insect will move on).
We have one pollinating bird in this province, the Ruby-throated Hummingbird. If you have moist soil, plant Cardinal Flower – it’s a short-lived perennial much loved by hummers.
What will make your yard pollinator-friendly?
All pollinators will benefit if these and other destructive behaviours, listed in the Holm book, are avoided
- Removing all leaves from the landscape
- Removing dropped branches and dead trees
- Removing plant stems in the fall
- Covering all bare soil where nesting can occur with mulch, rock or groundcover plants
- Applying pesticides
- Including plants treated with systemic insecticides during nursery production. Systemic insecticides are absorbed into the whole plant, from root to fruit, and may be present in pollen and nectar. The most commonly used systemic insecticides are neo-nicotinoids.
What do pollinators need?
First, native plants, those with which our pollinators share an evolutionary history. Bees will often ignore the non-natives or even the native cultivars and zero in on the natives. For reproduction, Lepitoptera (moths and butterflies) need ‘host’ plants with foliage their caterpillars are able to digest – 90 per cent of insects that eat plants can reproduce only on those with which they have co-evolved.
Second, a succession of blooms, so there’s food from early spring to late fall. And not just one of each plant – make a clump or a drift. If you see a milkweed with a lot of Monarch eggs on it, that - I learned from a webinar by Dr. Anurag Agrawal of the University of California - is because the butterfly was desperate. She prefers to distribute her eggs, in the knowledge that one plant can’t support many hungry caterpillars.
The accompanying table offers suggestions for season-long coverage by perennials that will attract many pollinators. Not included are woody species – shrubs and trees – which are important to pollinators as many flower much earlier than most perennials, and are also hosts. The oak genus is the champion among trees, hosting more than 400 species of Lepidoptera, according to University of Delaware entomologist and author Doug Tallamy. Here in the Great Lakes region, my favourite is the Red Oak.
Also not included are grasses that, along with sedges, host many Lepidoptera and provide habitat for ground-nesting bees. These can nest in the exposed soil between clumps of native warm-season grasses like Switch Grass, Indian Grass and Bottlebrush Grass. They can’t do that in areas of cool-season, mat-forming grasses such as lawns or hayfields.
Last but not least, provide water, in a shallow dish with pebbles added, so insects can get a drink without drowning. Change or refresh the water daily. For hummingbirds, make a 'nectar' mixture of one part sugar to four parts water, with no dye
. Change the mixture once a week, more frequently when it's hot.Pollinator Plant Table PDF