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Ornamental Grasses in Alaska
By Christine Bingham
Grasses are divided into two types based on how they synthesize their sugars: cool-season and warm-season. Cool-season grasses thrive in our climate, making their best growth with the air temperature around 60-75° Fahrenheit. Many different species and cultivars in this group grow in Alaska with great success. Warm-season grasses enjoy and are adapted to summers with high air temperatures, from about 80-95° F. Our cool summer climate makes these types of grasses challenging to grow. If you wish to try a warm-season grass, you will increase the probability of success by locating it in a place that gets all day sun and perfect drainage.
Photos copyright© Christine Bingham
Cultural requirements for grasses are hard to generalize, as there are so many different kinds. It is safe to say that grasses love sun and will usually be more successful in a sunny site as opposed to a shady one. Most enjoy a fertile soil just as much as the next plant, but are superbly adapted to growing in poor ones. Like most new transplants, they thrive when watered in well and irrigated their first two years, but after establishment are tolerant of all kinds of abuse and drought. Poor drainage, especially in our cold, wet springs, is a death sentence for many grasses. Be sure they are not planted too deep.
There seems to be a persistent idea that ornamental grasses cannot be grown in Alaska. Hopefully, this article can dispel that notion and encourage Alaskan gardeners to give this dynamic and useful group of plants a try.
Grasses to try in containers as annuals
The linear quality of grasses makes them a natural for contrasting the larger, rounder leaf shapes of most container plants. Many grasses are well suited to container cultivation with their pendant or pleasantly moundy or upright habits. Grass colors can also be used to great effect in containers. The grasses below are smaller selections that won't overwhelm their neighbors (unless otherwise noted) in a contained space.
Carex "Red Rooster"- leatherleaf sedge, caramel-colored, not hardy in zone 4, worth every penny, accents hot-colored neighbors in a container
Carex hachijoensis "Evergold"- Hachijo kan suge sedge, all the variegated sedges are good in containers, this one is beautiful, crisp variegation, to about 8 inches tall, usually doesn't over-winter in zone 4
Calamagrostis x acutiflora cultivars- feather reed grass, upright without staking, wonderful as a screen, hardy in-ground, some variegated selections/some all-green, provides a gentle rustling sound in breezes
Isolepis cernua- the "fiber-optic" grass is a great for adding a tufted, somewhat pendulous shape to containers, yellow green foliage, whitish blooms, cute as a button, might winter over in-ground in a protected area
Phalaris "Feesy's Form"- variegated and tinged with pink, (a rhizomatous runner, so don't plant in the border!), wonderful by itself in a pot, pleasant rustling sound in the wind
Nassella (Stipa) tenuissima - Mexican feather grass, sensational for lighting effects, an annual here, about 24", a feature even in winter
Grasses to try in the borders
Ornamental grasses in the border can reap multiple benefits for the gardener. When spaced at intervals they provide rhythm, a pattern for the eye to follow. They can function as a screen for ugly "plant ankles" on some plants like Delphinium or Baptisia. Many kinds are a real feature in the fall and winter garden. With the addition of some of the taller grasses, the slightest breeze will cause the garden to come alive with motion and sound. If you find your border is looking a bit fussy or static, try some of these beauties, which work equally well in groups, as specimens, or an accent.
Alopecurus pratensis 'Aureus' or 'Variegatus'- variegated foxtail grass, zone 4, glows in part shade, chartreuse, 1-2 feet, lovely accent plant in spring and early summer
Arrhenatherum elatius subsp. bulbosum 'Variegatum'- striped tuber oat grass, zone 3, up to 12", appears white from a few feet away, tufted shape in full sun
Briza media- common quaking grass/rattle grass, zone 4, flowers rustle pleasantly in a breeze to about 2.5 feet, lax tufts are a medium green
Calamagrostis x acutiflora 'Karl Foerster'- Karl Foerster feather reed grass, zone 3, medium green color, tall (7 feet!), upright
Calamagrostis x acutiflora 'Overdam'- variegated feather reed grass, zone 4, moundy shape, upright inflorescences from 4-5 feet, variegated with white edging
Deschampsia cespitosa 'Fairy's Joke'- tufted hair grass, zone 4, viviparous young on inflorescences (instead of seed), medium green tuft, 1-2 feet tall, a tropical look in flower
Deschampsia flexuosa 'Aurea'- golden crinkled hair grass, zone 4, foliage very fine (hair-like, hence the common name), up to 2 feet in flower, comes true from seed, a real feature in the spring garden
Helictotrichon sepmervirens- blue oat grass, zone 4, silver-blue color, about 30 inches, semi evergreen: do not cut back in fall
Hulten, Eric. 2003 edition. Flora of Alaska and Neighboring Territories: A Manual of the Vascular Plants. Stanford, California: Stanford University Press.
• Alaska Mill, Feed, and Garden Center- Anchorage