If you live in U.S. Department of Agriculture plant hardiness zone 5, you've likely experienced some cold winters, with temperatures falling as low as -20 degrees Fahrenheit in some years and the last frost usually arriving in late May. In spite of your cold winters, dozens of perennial plants exist from which you can choose when planning your garden. They range from plants that need lots of sun to many that tolerate shade, and also include types that grow from bulbs and varieties that are especially tolerant of dry spells or drought.
Nothing brightens a sunny bed or border quite like a mixed array of different perennials, with colorful flowers standing tall in the bright light. This sun-loving group includes the garden peony (Paeonia lactiflora), a clump-forming perennial renowned for its showy flowers that appear in spring. It blooms best in full sun, producing 4-inch wide flowers in many colors, depending on the cultivar, and grows in USDA zones 3 through 8. The daylily (Hemerocallis spp.) is another example of a sun-loving perennial that usually grows in USDA zones 3 through 10, although this can vary a bit according to the variety. As it name suggests, each large, six-petalled flower lasts only one day, but each plant produces dozens of blossoms in its long flowering season.
Perennials for Shade
If you have lots of shade in your garden, you can choose from a large group of perennials that thrive under these conditions, with many that have colorful flowers. The old-fashioned bleeding heart (Lamprocapnos spectabilis) is a tough, dependable perennial that grows in USDA zones 3 through 9 and loves a shady spot. It produces long, arching stems that carry nodding, heart-shaped, pink flowers in spring. Hostas (Hosta spp.), also called plantain lilies, make up another large group of perennials that thrive in shade. Often grown for their impressive, sometimes colorful leaves, they also have tall stalks of pastel-colored flowers in summer. Many types exist, including "Blue Shadows" (Hosta "Blue Shadows"), with bluish-green leaves, and "Fortunei Albo-Marginata" (Hosta "Fortunei Albo-Marginata"), with whitish-yellow, green-edged leaves. These hostas grow in USDA zones 3 through 8 and 3 through 9, respectively.
Perennials from Bulbs
Many perennials that do well in USDA zone 5 grow from bulbs rather than from the more common, fibrous root system of other perennials. These plants have an added advantage for gardeners -- once they're dormant, the bulb is easy to dig up and transplant to a new location, and many make small, new bulbs that you can separate from the parent bulb to grow more plants. Tulips (Tulipa spp.) are standouts in this group that grow in USDA zones 3 through 8. They come in dozens of flower shapes and colors, and make good cut flowers. Hybrid lilies (Lilium spp.) make up another group of perennials that grow from a bulb, although this bulb is a bit unusual because it's made up of many circularly arranged, fleshy scales. Lilies generally grow in USDA zones 3 through 8 and are organized into eight groups, or divisions, based on their origin and flower type.
Perennials for a Dry Area
If your part of USDA zone 5 tends to be dry and rain is often scarce, don't despair. A group of perennials called sedums or stonecrops (Sedum spp.) thrive in dry conditions, storing moisture in their thick, succulent leaves. Sedums can be tall, medium-sized or short and creeping, and some have attractive, colorful flower heads late in the season. For example, "Autumn Delight" (Sedum "Autumn Delight") has large clusters of magenta flowers on strong, upright stems, while fish-scale sedum (Sedum tetractinum) has small, flattened yellow flowers on scale-like leaves. These plants grow in USDA zones 3 through 9 and 4 through 8, respectively. The coreopsis, or tickseed plant, (Coreopsis verticillata "Moonbeam") is another perennial that tolerates dryness well and also thrives in poor, rocky soil. It has pale yellow flowers covering the bushy plant in summer and grows in USDA zones 3 through 9.