If your beds are full of roses, lilies and peonies, you won't attract many butterflies. Unfortunately, most of these plants produce very little nectar. As a rule, perennials produce more nectar than annuals, with a few exceptions: common heliotrope (Heliotropium arborescens), cosmos (Cosmos bipinnatus) and Mexican sunflower (Tithonia rotundifolia) are good sources of food.
It's best to offer a variety of plants, including perennials, annuals, herbs, climbers and shrubs.
Choose simple flowers, which generally produce larger amounts of more readily accessible nectar.
Plan for a succession of blooms from May to October. You'll be sure to see butterflies in your garden all summer long if you provide them with a constant source of nectar.
While you should start with highly fragrant yellow or mauve flowers, remember that a wide palette of colours will be very attractive for both you and your winged guests.
Add a few "star" species to your garden, a few plants that are particularly attractive for butterflies, including spotted Joe-pye weed, milkweed, yellow sage and star cluster, to improve your chances of success.
Butterfly bush (Buddleja davidii) is another plant that is well-known for being irresistible to many butterfly species. It is not very hardy in the Montréal region, however, even with winter protection.