Wild bergamot (Monarda fistulosa). Photo: Wikimedia Commons, CC BY-SA 3.0.
Who pollinates Canadian gardens
Canada has over 800 native bee species, the majority of which are solitary rather than colonial. Unlike honey bees — which are non-native and managed — these native bees nest in the ground, in hollow stems, or in wood cavities. They are efficient pollinators but largely invisible to most gardeners.
Bumble bees, which are colonial native bees, are the most recognizable group. They emerge early in spring when most other pollinators are still dormant and are capable of foraging at lower temperatures. This makes them disproportionately important for early-blooming native plants.
Monarch butterflies (Danaus plexippus) migrate through Canada each summer and require milkweed (Asclepias species) as the sole larval host plant. Adult monarchs feed on nectar from a wider range of flowers, but their breeding success in Canada depends on milkweed availability.
Continuous bloom through the season
One of the most effective things a garden can do for pollinators is provide flowers across the full growing season — from early May to late October in most of southern Canada. A garden that blooms only in July and August provides resources during the peak season but leaves pollinators without support during critical early and late periods.
Early season (May–June)
- Wild columbine (Aquilegia canadensis) — blooms April to June; one of the first native flowers available to bumble bees and ruby-throated hummingbirds after winter
- Bloodroot (Sanguinaria canadensis) — very early bloomer in woodland gardens; March to April
- White beardtongue (Penstemon digitalis) — blooms May to July in open, well-drained sites
Mid season (July–August)
Cardinal flower (Lobelia cardinalis). Photo: k yamada, Wikimedia Commons, CC BY-SA 2.0.
- Purple coneflower (Echinacea purpurea) — July through September; long-blooming and highly attractive to bumblebees and specialised long-tongued bees
- Wild bergamot (Monarda fistulosa) — July to August; tubular flowers attract bumble bees, hummingbirds, and clearwing sphinx moths
- Cardinal flower (Lobelia cardinalis) — July to September along moist edges; adapted for hummingbird pollination
- Butterfly weed (Asclepias tuberosa) — June to August; an important milkweed species for monarch breeding in drier upland sites
Late season (September–October)
- Canada goldenrod (Solidago canadensis) — one of the most important late-season nectar sources; supports over 100 insect species
- New England aster (Symphyotrichum novae-angliae) — September to October; critical for bumble bee colonies building winter reserves
- White snakeroot (Ageratina altissima) — blooms through October in partial shade; valuable for late-season specialist bees
Nesting habitat
Plant diversity alone is insufficient for a fully functional pollinator garden. Most native bees also need suitable nesting sites, which are largely absent from conventional landscaping.
Ground-nesting bees — roughly 70% of Ontario's native bee species — require areas of bare or sparsely vegetated soil with good drainage. This can be provided by leaving small patches of soil exposed (15–30 cm across is sufficient for many species), particularly in a south-facing location that receives direct sun.
Cavity-nesting bees include mason bees and leafcutter bees, which use hollow stems, existing wood cavities, or holes in wood. Leaving the hollow stalks of native plants (goldenrod, cup plant, Joe-Pye weed) standing through winter provides nesting material. Bundles of hollow bamboo or elder stems arranged in a sheltered, south-facing location can supplement natural cavity availability.
Dead stalks and plant stems should be left standing until late May or June — not cut back in fall or early spring. Many native bee larvae overwinter inside stems and emerge only after consistent warm temperatures in late spring.
What to avoid
Several common garden practices reduce pollinator value or actively harm native bee populations:
- Pesticides — insecticides, fungicides, and some herbicides are documented to harm native bees at sublethal doses. This includes systemic neonicotinoids applied as soil drenches or pre-treated seed coatings.
- Excessive tidiness — removing leaf litter eliminates overwintering habitat for bumble bee queens, ground beetles, and many other beneficial insects.
- Double or sterile flowers — cultivated varieties with doubled petals (bred for ornamental density) often have reduced or absent pollen and nectar. The straight species is generally more valuable than named cultivars.
- Non-native ornamental plants — while some non-native flowers provide nectar, they rarely support specialist native bee species that require specific native plant genera for larval pollen.
Milkweed and monarchs
Milkweed (Asclepias) flowers — larval host for monarch butterflies. Photo: Tortie tude, Wikimedia Commons, CC0.
Monarch butterflies breed across Ontario and Quebec during their summer migration. Female monarchs lay eggs exclusively on milkweed leaves. Caterpillars feed on milkweed foliage for two to three weeks before pupating.
Common milkweed (Asclepias syriaca) is the most widespread species in Ontario and supports the highest monarch caterpillar densities where documented. It spreads aggressively by rhizome in disturbed soil, which makes it suitable for larger areas but potentially problematic in small gardens. Butterfly weed (Asclepias tuberosa) is a more restrained alternative suited to drier garden conditions.
Information on Ontario monarch populations and migration corridors is maintained by Pollinator Partnership Canada and Monarch Watch.
