Native ornamental grasses provide big benefits to Minnesota gardens

I like to say that a plant has to earn its place in my garden. I compare choosing a plant to interviewing job candidates — what will they contribute? How will they fit in? What are their unique qualities?

When it comes to ornamental grasses, native species such as bluestem, grama, switch grass, Indian grass and others have such an impressive résumé that I'd hire them on the spot.

Native grasses offer year-round interest. However, late summer and fall are when they really shine, literally. Walking or driving around town, you'll notice their graceful plumes and airy blooms backlit again the August light and wonder, what is that gorgeous grass? Now is the time to shop and plan for these particularly American beauties.

Besides their stand-alone good looks, native grasses help pull together the landscape, their lines and texture giving the garden a more natural appearance. They can find a use in modern or formal settings. Here are some more reasons to add these grasses to your garden (a few may surprise you):

Native grasses require little upkeep; just whack them back in the spring. They thrive with low nutrients; in fact, too much fertilizer makes them floppy, so no need to feed. With few pests or diseases, you can do without pesticides, which is a plus for the birds and other wildlife that depend upon them for cover and sustenance.

The roots of native grasses go deep, usually around 3 to 5 feet, with some as deep as 15 feet underground. The roots continually die and regenerate, adding organic matter to the soil and recycling nutrients. The roots are incredibly efficient at absorbing and filtering rainwater, while preventing soil erosion. As a bonus, their fibrous nature helps to choke out weeds in the area surrounding the plants.

A number of native butterflies, some endangered, depend upon native grasses as a larval host plant. Often overlooked in butterfly gardens, skippers are the smaller, tawny-colored butterflies with the folded wings often mistaken for moths. Just like other pollinators, they are threatened by habitat loss. Their larvae (caterpillars) weave together the grass blades near the plant's base to build a shelter that provides food and protection before they pupate and become butterflies.

Use this University of Minnesota-produced poster to determine the grasses utilized by different butterfly species: bit.ly/2MoNlDP

Native grasses grow quickly, usually reaching their mature size in three years. While striking as individual specimens, in larger numbers, they can be used for specific garden jobs. Their vertical habit lends itself to screening for privacy or defining spaces. Mass plantings can be used for ground cover. Hide an ugly air conditioner or other utility behind them. Lacking flowers that attract insects or dump potential debris, they are perfect for poolside plantings.

Grasses are special, in that they create movement in the garden as they sway in the breeze, and beyond that, sound. Susurration is a word used to describe a murmur or whisper, such as the sound of the wind rustling through the blades. Not many plants can claim that. The same rustling sensation in native grass plantings can be used to evoke water in the landscape, as they ripple back and forth through the air.

Little bluestem is a warm-season, clumping grass that combines well with other native flowering perennials and shrubs. It grows best in full sun and well-drained soil. In fall, the upright blue-green foliage turns rose-gold, red or maroon, depending upon the cultivar. It provides food (and sometimes shelter) for the larvae of 15 butterfly and moth species found in the Upper Midwest. Blue Heaven™ (University of Minnesota) has stunning color, while Standing Ovation stands up to snow.

Blue grama is a drought-tolerant, warm-season, clumping form that grows to a foot tall, sometimes used as a lawn alternative. The tan blooms look like little flags waving in the breeze. Blonde Ambition is a popular cultivar. It's another native grass used for food by a number of skippers and moths.

Prairie dropseed has fine-textured slender blades that create a fountain of foliage. It is very effective as a ground cover planted en masse, although it will flatten somewhat as the season progresses. It turns yellow to bronze in fall, and when blooms are finished, little round hard seeds drop to the ground (hence the name), a favorite food for sparrows, juncos and other birds. The fragrant plant smells like coriander, licorice or buttered popcorn, according to whom you ask.

Indiangrass, at 5 to 7 feet tall, is a striking beauty that adds architecture and color. It is adaptable to different soil conditions. Spread by underground rhizomes, it is more suited to larger planting areas than small garden beds. The golden seed heads are attractive to birds and wildlife.

Also consider these other native grasses: sideoats grama, switch grass, prairie Junegrass, lake sedge, big bluestem and prairie cordgrass.

Master gardener Rhonda Fleming Hayes is a Minneapolis-based writer who blogs at thegardenbuzz.com. She is the author of "Pollinator-Friendly Gardening: Gardening for Bees, Butterflies and Other Pollinators," available at Amazon.com.