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by High Country Gardens

Bouteloua 'Blonde Ambition' with Cotoneaster, Agave and Oputia.
Bouteloua 'Blonde Ambition' with Cotoneaster, Agave and Oputia.

Ornamental grasses have gained a lot of popularity in recent years.  And as an ornamental grass enthusiast, I’m pleased to see that their popularity shows no signs of abating.  Different from lawn grasses, ornamental grasses are grown individually or in groups to show off their ornamental flower spikes, seed heads and interesting foliage.  They are not to be mowed to create a green carpet in your yard.

There are essentially two types of ornamental grasses: cool season growers and warm season growers. To understand how to use both types of grasses in our gardens and landscapes, this designation is important.

Cool season grasses like cool weather, so their foliage greens up and begins growing in early spring.  Flowering is soon to follow and happens in late spring or early summer.

Warm season grasses don’t begin to wake up from winter dormancy until the seasonal temperatures begin to warm up.  They typically begin to grow in late spring.  Flowering occurs later, in mid- to late summer and fall depending on the species.

Nassella tenuissima
Eriogonum umbellatum with Nassella tenuissima.

Ornamental grasses are dependable, durable and easy-to-grow. They provide texture and color with their foliage.  Their flower spikes are very beautiful and graceful, as are their seed heads that ripen from the flowering spikes. They are especially good companions for flowering perennials, Yucca, Agave and shrubs. Grasses should be left standing over the winter to provide essential garden interest.  Grasses are beautiful when the frost covers them with a delicate coat of ice or frozen dew. They sway gracefully in the wind and are unsurpassed at capturing the low angled sunlight in early morning and late afternoon.

Maintenance is simple. Cut ornamental grasses back hard in early to late spring: cool season growers in early spring and warm season growers in mid- to late spring or as soon as they begin to show a little new green growth.  Fertilize in the fall with a top dressing of compost and Yum Yum Mix scratched into the soil’s surface, watered in and covered with mulch for the onset of winter.

Some of my favorites include both cool season and warm season species.

Festuca (Festuca ovina) is a cool season genus known best for its smaller size and typically striking blue foliage.  ‘Boulder Blue’ is a superb selection made from a Boulder, Colorado landscape and is the best of a number of Festuca ovina selections. ‘Sea Urchin’ is well named and it’s a sturdy dwarf variety only 8” tall in flower.  It’s a superb little blue tufted grass for edging beds, paths and walkways.

Calamogrostis Karl Foerster and Russian Sage.
Calamogrostis 'Karl Foerster' and Russian Sage

Silky Thread Grass (Nassella tenuissima) is very popular cool season species, known for its ultra-fine bright green foliage, tawny seed heads and movement in the slightest breeze.

Blue Grama Grass ‘Blonde Ambition’ (Bouteloua gracilis)is a High Country Gardens introduction and one of the most unique ornamental grasses to be introduced in recent years. This warm season grass is a star in the landscape with hundreds of flag-like chartreuse flowers that turn to blonde seed heads that hold through winter into spring.

‘Karl Foerster’ Feather Reed grass (Calamagrostis acutiflora) is another fantastic cool season grass with a tidy up-right form and eye catching wheat colored seed heads that hold on the plant for 6 months or more.