Ornamental Grasses for Western Montana Landscapes

What is the difference between cool-season and warm-season grasses?

Colorado State University Extension's fact sheet Ornamental Grasses (7.232) explains that some grasses grow best in cool temperatures and others in warm temperatures, and labels each grass accordingly. Cool-season grasses green up early, look their best in spring and early summer, and often flower in early summer. Warm-season grasses are slow to start, wait for heat, and peak in late summer and fall, usually with stronger fall color.

In western Montana's short season that difference matters. Cool-season grasses give the garden structure in May when warm-season grasses are still brown stubble; warm-season grasses carry the fall. A mix gives the longest season. This guide is part of our Montana Landscaping, Lawn & Irrigation Guide.

Which native grasses grow well in western Montana yards?

The 2025 MSU MontGuide Native Plants for Montana's Home Gardens lists grasses and sedges with hardiness zones. Bunchgrasses of the region include Idaho fescue (zones 4 to 8), bluebunch wheatgrass (3 to 7), prairie Junegrass (3 to 9) and Sandberg bluegrass (4 to 7). Showier choices for beds include little bluestem (4 to 10), blue grama (3 to 10), sideoats grama (3 to 9), prairie dropseed (3 to 8), Indian ricegrass (3 to 9) and big bluestem (3 to 8). For dry shade under pines, MSU lists Geyer's sedge (5 to 10) and needleleaf sedge (3 to 7).

MSU marks which of these are Montana natives and which are native to neighboring states. Its pollinator article recommends replacing some traditional turf with native flowering plants, bunchgrasses and clumping sedges. See replacing some lawn with native plants for that conversion.

Which ornamental grasses work best here?

CSU's fact sheet profiles the grasses most often sold in the Rocky Mountain region. Feather reed grass (Calamagrostis 'Karl Foerster') is cool season, 2 to 3 feet, upright, with flower spikes that persist into winter. Blue avena, or blue oat grass, is cool season, about 2.5 feet, semi-evergreen with blue foliage, for sun to light shade. Blue fescue is cool season, 6 to 18 inches, excellent for sandy ground but not heavy, wet soils, and CSU says it should be divided often to renew it.

Among warm-season grasses CSU lists little bluestem (2 to 3 feet, drought tolerant, orange to red fall color, best in clay), switchgrass (4 to 5 feet, a native with yellow fall color that tolerates soil extremes) and blue grama (1 to 1.5 feet, a native clump grass for unirrigated areas, intolerant of shade). Those three are also in MSU's native list.

Will Miscanthus and fountain grass survive a Montana winter?

Be cautious. CSU notes that some fountain grass varieties freeze out in the coldest winters, that tender fountain grass is grown as an annual, and that giant silver grass does not bloom every year in Colorado. Those are Colorado observations, and western Montana's winters and shorter season are generally no kinder. Maiden grass (Miscanthus sinensis) cultivars are widely sold; CSU notes that Miscanthus needs ample water, which makes it a poor fit for a low-water bed.

If you want a tall, dramatic grass that is sure to return, switchgrass and big bluestem are the safer bets. Buy from local nurseries and ask what has overwintered for them.

Which grasses spread too much?

CSU flags blue lyme grass as quite invasive in loose soils, and ribbon grass as needing to be enclosed to keep it from spreading. It also notes that some grasses reseed. Running grasses are best confined by a deep edging or used only where a spreading groundcover is the goal, such as a bank.

Know the weedy grasses too. On the Montana Noxious Weed List (effective June 21, 2019), ventenata is a Priority 2A noxious weed and cheatgrass is a Priority 3 regulated plant. Neither is an ornamental, but both invade disturbed ground around new plantings, and recognizing them early is part of keeping a grass bed clean. Our guide to Ravalli County noxious weeds covers identification and the landowner duty.

When should ornamental grasses be cut back?

In spring, just before new growth starts. CSU says most grasses benefit from being cut back then, and recommends hedge shears and gloves because some species have razor-sharp leaf edges. Leaving the foliage standing through winter protects the crown, gives the garden structure in snow, and, according to MSU's bee habitat MontGuide, the cut stems of grasses such as basin wild rye can host stem-nesting bees when left at varying heights.

Near a house in fire country, the calculation changes. MSU's fire-resistant plants MontGuide says a plant's flammability depends partly on how much dead, dry material it accumulates. A clump of cured grass against siding or under a deck is a fuel bed. Cut back grasses within the first five feet of a building in fall, or keep them out of that zone entirely; see Zone 0 and fire-resistant plants.

How and when do you plant and divide grasses?

CSU recommends spring planting, and says container-grown grasses can be planted through the season until about a month before the first frost. It warns that late planting of divisions is not recommended, particularly for warm-season types. For seeded native grasses, MSU's 2025 MontGuide says late fall is often the best time to sow, because many native seeds need a cold period to germinate, though fall seeding may fail on exposed, windswept sites with little snow.

Division renews old clumps that have died out in the center. CSU notes that many perennial grasses form root masses that are very difficult to divide, so dividing is easier when clumps are still young. See frost dates for timing.

How much water do ornamental grasses need?

Less than turf, and it varies with size. CSU's rule of thumb is that among native grasses, the taller the grass, the more water it needs. Blue grama is suited to unirrigated areas once established; Miscanthus wants ample water. Blue fescue needs some supplemental water according to CSU.

Group grasses with plants of similar water need so they can share a drip zone; see xeriscaping for how hydrozones work.

Do grasses need fertilizer or special soil?

Rarely fertilizer. CSU's fact sheet recommends mulch but does not call for fertilizing ornamental grasses, and the NRCS booklet Creating Native Landscapes notes that most soils in the region are alkaline, which the native bunchgrasses are adapted to. The bigger soil concern is drainage: blue fescue in particular does poorly in heavy, wet soil, per CSU. MSU recommends a soil test before planting any bed; see soil testing for Montana yards.

Can a native grass meadow replace part of a lawn?

On larger lots, yes. The NRCS booklet Creating Native Landscapes describes restoring larger areas to native prairie or meadow by seeding mixtures of grasses and wildflowers, seeding a simple mix and interplanting, or transplanting. It says that once established, native prairies or meadows are virtually maintenance free. It also notes that native grasses can make a mowed lawn, seeded far more densely than a meadow (about 500 pure live seeds per square foot for a lawn against about 25 for a prairie stand), and rates blue grama and buffalograss as short, infrequently mowed warm-season choices with late green-up.

The establishment years are the hard part. NRCS stresses that weed control is critical until the cover is dense enough to crowd out unwanted plants. Our guide to landscaping a rural acreage covers meadow conversion at a larger scale.

How do you design with ornamental grasses?

Use them in groups and repeat them. A single grass reads as a weed; a drift of five or seven reads as a decision. Tall upright grasses such as feather reed grass make a screen or a vertical accent; low mounding grasses such as blue fescue edge a path; mid-size natives such as little bluestem and prairie dropseed pair with perennials like blanketflower, penstemon and coneflower. MSU's bee habitat MontGuide suggests leaving small areas of bare soil around ornamental grasses for ground-nesting bees.

Grasses also suit slopes: the NRCS booklet calls grasses that spread by rhizomes, stolons or tillers prime candidates for ground cover and site stabilization; see landscaping a slope and erosion control on slopes. Grasses also pair naturally with boulders and gravel paths; see landscaping with boulders and native rock.

Can HJ plant ornamental grasses?

Yes. Grass and perennial beds are part of our landscaping design work, including soil preparation, drip irrigation and mulch, and our seasonal cleanups can handle the spring cut-back. For broader plant choices see hardy perennials and shrubs for western Montana.

Call HJ Property Care & Tree Service at (406) 215-7319 or request a free estimate and we will walk the property with you.

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