Those who live in the colder hardiness zones may not have as many perennial flowers to choose from as those in the more temperate zones, but what they do have to choose from are strong and tough and yet produce beautiful and colorful flowers. Hardiness zone 3 is the coldest zone where perennials can grow. Zones 1 and 2 are only in the coldest parts of Canada and Alaska. Zone 3 is in coastal Alaska, southern Canada, Maine, Vermont, upstate New York, the northern Midwest and Montana, and the higher elevations in Wyoming, Utah and Colorado also fall in this zone.
Yarrow (Achillea spp) is hardy in all but southern Florida and southern California. The plant grows from 18 to 36 inches in height and 24 to 36 inches in width. It produces small semi-evergreen leaves that, in most varieties, resemble those of a fern and pink, yellow or white flowers that can be single or double flowers with extra petals. They bloom from spring through fall. Yarrow needs full sun---at least six hours of sunshine per day---and can grow in sand, loam or clay soils, as long as it is well drained. Yarrow is an herb that can be grown as a border for a perennial bed, in edging or in a mass planting all its own. It can be used in fresh or dried flower arrangements. The stalks will bend over as they grow, making the plant a good choice for a ground cover. They actually do better in cooler areas than in where there is heat and humidity.
Wild ginger (Asarum canadense L.) will grow to only 4 to 8 inches in height. The plant produces large, heart-shaped deciduous leaves with the softness of velvet and a single flower that can be a dark red/brown or green/brown in color. It blooms in April, May and June and grows at the junction of two leaves at ground level. The roots spread out to produce more plants, and the result is a densely packed ground cover. Wild ginger is hardy in zones 3 through 7 and needs partial to full shade and rich, moist soils. The plant is a good choice for a butterfly garden.
Snowdrop (Anemone sylvestris) blooms late in the spring producing tall---12- to 15-inch---stems with a single pure white flower that measures 2 inches across and dark green leaves that grow at ground level. The plant grows from rhizomes, underground roots that grow horizontally instead of vertically. The rhizomes spread out from 12 to 18 inches, producing enough plants to form a ground cover. The plant is hardy in zones 3 through 8 and needs full sun or partial shade and moist soil.