By Christine Bingham
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.
The true grasses belong to the very large family Poaceae. There are about 10,000 species and more than 600 genera. The sedges, family Cyperaceae, are often lumped together with the true grasses, as are the family Juncaceae, the rushes, and Typhaceae, the cattails. Alaska has around 200 or so species of true grasses, over 150 species of sedges, about 35 rushes, and one lone species of cattail.
Grasses come in almost every color of the foliage rainbow: red, orange, yellow, blue, green, many types of variegated, and gray, to name a few. They come in silhouettes ranging from spiky to moundy to upright and everything in between. Grasses hardy in Alaska come in sizes that span tiny rock garden gems to beauties taller than you or me! There are grasses that enjoy wet soil, even growing into the water, and grasses that tolerate very dry conditions.
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.
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.
Grasses are some of the most pest-free plants available. When properly sited, they rarely suffer from disease, either. In dry weather, aphids occasionally appear on certain types of grass. Foliar rust crops up sometimes in humid and warm weather but it is hardly noticeable and is minimized by planting in a situation with plenty of air movement. Attention to siting and cultivation requirements minimizes the chances for infestations or disease.
Ornamental grasses increase in size by "running" or "clumping." Clumpers increase their diameter a little each year, just like most other perennials. The running types increase by rhizomes or stolons and must be scrutinized before (and meticulously maintained after) planting, as they can be quite difficult to remove once established. Almost every ornamental grass sold in Alaska is the clumping type. The only ornamental running grass commonly sold in Alaska is Phalaris arundinacea "Feesey's Form" (or another Phalaris cultivar).
If your garden is near an ecologically sensitive area, you can include most grasses in your plan without concern. Many popular cultivars are sterile, for example, Calamagrostis x acutiflora cultivars, and so won't seed around. Grasses deemed invasive because they go to seed in other parts of the world do not flower in our state because of our short growing season (one example: Miscanthus spp.). Of the grasses that do go to seed here, such as Festuca and Deshampsia flexuosa "Aurea", the increase is very polite and nearby the mother plant and easy to remove, if desired. All plants recommended in this article are clumpers and not runners, with the exception of one (noted below) for container planting.
Cold hardiness of many grasses is unknown. Grasses listed in the literature recently as hardy to zone 7 are now listed as zone 5 (Calamagrostis and Isolepis come to mind). Listed hardiness ratings are often conservative and as more people grow grasses in cold climates, a more accurate zone boundary will emerge. All grasses listed in this article have been hardy in-ground for the author for at least three years unless otherwise noted. Leaving grass foliage intact over winter is one way to protect the crown in case of no snow cover.
Grass "clean up" should be saved until spring. Many people cut their perennials back in autumn to avoid pest and disease problems but since grasses do not suffer greatly from either, there is no compelling reason to cut them down before spring. Some semi evergreen grasses even resent being cut back in autumn and may grow back in spring only weakly or not at all, for example Festuca and Helictotrichon. Additionally, the beauty of grasses left intact through winter is a great attribute in a subdued season. In spring, cut back to about 3 or 4 inches for most types of grass. For the tufting semi evergreen types and sedges, cutting back is not necessary. Dead foliage can be teased out with the fingers if desired.
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
Festuca "Elijah Blue"- blue/gray leaved, wonderful with jewel tones, great for textural contrasts, can be used as a perennial in the border but do not cut back in fall
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
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 'Avalanche'- variegated feather reed grass, zone 4, moundy shape, upright inflorescences to about 4 or 5 feet, reverse variegated with green edging and white centers
Calamagrostis x acutiflora 'Eldorado'- variegated feather reed grass, zone 4, moundy shape with upright inflorescences to about 4 feet, variegated light yellow with green edging
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 cespitosa 'Schottland'- Scottish tufted hair grass, zone 4, small, light green tuft, about 2-3 feet in flower, excellent for massing
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
Molinia caerulea 'Variegata' - variegated purple moor grass, zone 4, creamy stripes on foliage up to 12"
Sesleria heufleriana- blue-green moor grass, zone 4, tufted to about 15", blue-green color, black flowers with white pollen sacs are striking
Hulten, Eric. 2003 edition. Flora of Alaska and Neighboring Territories: A Manual of the Vascular Plants. Stanford, California: Stanford University Press.
Darke, Rick. 2007. The Encyclopedia of Grasses for Livable Landscapes. Portland, Oregon: Timber Press.
• Alaska Mill, Feed, and Garden Center- Anchorage
• Evergreen Landscape and Nursery Supply- Anchorage
• Fritz Creek Nursery- Homer
• Home Depot- Anchorage, Fairbanks, Juneau, Kenai, Wasilla
• In the Garden Nursery- Anchorage
• Lowe's- Anchorage, Fairbanks, Kenai, Wasilla
• Sutton's Greenhouse- Anchorage
• Bluestem Nursery- http://www.bluestem.ca
• Forest Farm Nursery- http://www.forestfarm.com
• Digging Dog Nursery- http://www.diggingdog.com
• Bluestone Nursery- http://www.bluestoneperennials.com
Photos copyright© Christine Bingham