Winter temperatures in Canada's northernmost territory, Nunavut, can dip lower than minus 50 degrees F. Those temperatures can discourage almost any garden perennial. Much of Lower Canada, however, lies in USDA Plant Hardiness Zones 3 or above, with minimum temperatures of minus 30 degrees F or higher. Many perennials, given adequate winter protection, will make effective garden bedding plants in these parts of Canada.
Fireweed (Epilobium angustifolium), sometimes called willow herb because of its narrow green leaves, grows wild in all 10 of Canada's provinces. It's especially abundant in recently burned areas, where it's one of the first flowers to appear after a wildfire. Cultivated in home gardens, fireweed makes a striking summer-blooming addition to the middle or back of a perennial border. Standing from 3 to 6 feet high, it has showy late-summer spires of deep pink flowers.
The plant's young shoots make a good vegetable, says the Coalition of Canadian Health Care Museums, and its young leaves work well as salad greens. Fireweed's only shortcoming is that in rich soil it will become invasive. Contain it by planting it in a dry spot with poor soil and removing the dead flower stalks before they drop their seeds.
Creeping germander (Teucrium canadense) is a perennial herb of the mint family. A spreading plant that grows 6 to 8 inches high and up to 2 feet wide, it's useful as an herb garden edging, ground cover or in rock gardens. Creeping germander brightens the garden with yellow springtime leaves that become lime-green in mid- and-late summer. Spikes of delicate pink blooms attractive to butterflies make an effective contrast with the leaves. Plant drought-tolerant and deer-resistant creeping germander in sun to part shade. Hardy in Zone 4 and above, this low-maintenance plant accepts moist or dry sand, clay and loam soils in a wide pH range.
False Sunflower "Bressingham Dubloon"
False sunflowers (Heliopsis helanthoides), says the Lady Bird Johnson Wildflower Center, are perennials native to the Canadian provinces of Ontario, Quebec, Saskatchewan and Manitoba.They grow wild in the moist sandy soils of open woods and fields, reaching between 3 and 5 feet tall. Between June and September, wild false sunflower has bright yellow 2-inch daisy-like flowers with raised yellow centers.
A false sunflower cultivar, "Bressingham Dubloon" stands from 4 to 6 feet high and 3 to 5 feet wide. Removing its spent flowers promptly will extend its blooming season from early summer to mid-autumn. Luxuriant double golden yellow blooms with yellow centers appear even brighter against its deep green foliage. Plants in very fertile soil may need staking. Otherwise, this is an easy-care perennial. Hardy to Zone 2, it likes full sun and sand, loam or clay soil of average moisture.