Flowers feed pollinators, but they are only half of a working habitat. Bees and butterflies also need places to nest, shelter from weather, somewhere to overwinter and, for butterflies, the specific plants their caterpillars eat. Many of these features cost nothing and amount to doing slightly less tidying. This note covers the structural side of a Canadian pollinator garden.
Nesting sites for bees
Most of Canada's wild bees are solitary, and the majority of those nest in the ground. A patch of bare, undisturbed, well-drained soil in a sunny spot gives ground-nesting bees somewhere to dig. Heavy mulch over every surface, by contrast, removes that option.
Other bees nest in cavities — hollow stems, old beetle tunnels in wood, or pithy plant stalks. Leaving some standing stems over winter, and cutting them back only partially in spring, preserves these nesting sites.
Leave a sunny patch of bare ground, keep some standing dead stems, and delay the spring cleanup until temperatures are reliably warm. Much pollinator habitat is created simply by not removing it.
Host plants for butterfly caterpillars
Adult butterflies sip nectar from many flowers, but their caterpillars are often far choosier. The clearest example is the monarch, whose caterpillars feed only on milkweeds (Asclepias). A garden can be full of nectar and still raise no butterflies if it lacks the host plants their larvae depend on.
Planting host species alongside nectar flowers lets a garden support the full life cycle rather than just feeding passing adults.
Water and shelter
Pollinators need water, but open dishes can drown small insects. A shallow tray with pebbles or sand for insects to land on, topped up in dry weather, gives them a safe place to drink. Butterflies are sometimes seen gathering at damp ground, drawing up moisture and minerals.
Shelter from wind matters too. A hedge, shrub layer or even a fence line creates calmer air where insects can forage and rest. Mixed plant heights give cover at different levels.
Reducing harm
The most direct thing a garden can do is avoid insecticides, including systemic products that move into pollen and nectar. Tolerating some leaf damage, and accepting a less manicured look, removes the usual reason to spray.
- Avoid insecticides, especially systemic treatments on flowering plants.
- Confirm purchased plants were not pre-treated before flowering.
- Leave leaf litter and standing stems through winter where you can.
Noting which bees and butterflies appear, and when, builds a picture of how the garden is doing over time. Community science platforms such as iNaturalist let observations be identified and shared.
Putting it together
Habitat works best as a combination: native flowers in sequence, host plants for caterpillars, undisturbed nesting ground, a little water and shelter, and no spraying. For the plants themselves see the native plants note, and for arranging their flowering see the bloom timing note.