Ornamental Grass for Cold Climates
Ornamental grasses are usually divided into two categories: cool-season grasses or warm-season grasses.
Cool-season grasses sprout up quickly in spring, bloom in early summer, may go dormant in the heat of mid-late summer, and then grow again when temperatures cool in early autumn. Warm-season grasses can be slow growing in spring but really take off in the heat of mid-late summer and bloom in late summer and fall.
Growing both cool-season and warm-season can provide year-round interest in the landscape.
Cool Season Ornamental Grasses for Zone 4
Feather Reed grass – Feather Reed grass has early plumes that are 4- to 5-feet (1 to 1.5 m.) tall and cream-colored to purple depending on the variety. Karl Foerster, Overdam, Avalanche, and Eldorado are popular varieties for zone 4. Tufted Hairgrass – Generally, reaching 3-4 feet (1 m.) tall and wide, this grass likes sun to part shade locations. Northern Lights is a popular variegated cultivar of tufted hairgrass for zone 4. Blue Fescue – Most blue fescue is dwarf and clump forming with bluish grass blades. Elijah Blue is popular for borders, specimen plants, and container accents in zone 4. Blue Oat grass – offering tall clumps of attractive blue foliage, you can’t go wrong with blue oat grass in the garden. The variety Sapphire makes an excellent zone 4 specimen plant.
Warm Season Ornamental Grasses for Zone 4
Miscanthus – Also called maiden Grass, Miscanthus is one of the most popular cold hardy grasses for the garden. Zebrinus, Morning Light, and Gracillimus are popular varieties in zone 4. Switchgrass – Switchgrass can get 2 to 5 feet (0.5 to 1.5 m.) tall and up to 3 feet (1 m.) wide. Shenandoah and Heavy Metal are popular varieties in zone 4. Grama Grass – Tolerant to poor soils and cool temps, both Side Oats Grama and Blue Grama are popular in zone 4. Little Bluestem – Little Bluestem offers blue-green foliage that turns red in fall. Pennisetum – These small fountain grasses typically don’t get larger than 2 to 3 feet (0.5 to 1 m.) tall. They may need extra protection in zone 4 winters. Hameln, Little Bunny, and Burgundy Bunny are popular in zone 4.
Planting with Zone 4 Ornamental Grasses
Ornamental grasses for cold climates require little maintenance. They should be cut back to 2-4 inches (5-10 cm.) tall once a year in early spring. Cutting them back in autumn can leave them vulnerable to frost damage. Grasses provide food and shelter for birds and other wildlife in the winter. Not cutting them back in early spring can delay new growth. If older ornamental grasses begin to die in the center or just aren’t growing as well as they used to, divide them in early spring. Certain tender ornamental grasses, like Japanese Blood grass, Japanese Forest grass, and Pennisetum may need extra mulch for winter protection in zone 4.
