Garden Guy: The Grasses of Autumn

Grasses at site of Custer's Last Stand by sah-archipedia.org

By Bruce Bennett

One of my main enjoyments in the months of September - November is the sight of ripening grasses in various landscapes. Hence, the reason for this month’s column which begins more like the old elementary school ‘What I did On My Vacation’ assignment. 

You know the kind; we all wrote them in the fifth grade or thereabouts. However, my retelling of the tale does not take place in 1959, but, rather, in 2009. The event was part of a cross-country and back road trip. 

The part of the journey which comes to mind most often took place in southeastern Montana, near the little town of Hardin. The area is now known as the Little Bighorn Battlefield National Monument (AKA, Custer’s Last Stand). 

The area is austere in its beauty, with big blue Montana skies, the wind and the ever-moving autumn sea of grass with its own particular susurrations in the air. They were truly awe-inspiring views and a balm for this city-surrounded soul. 

Very few of us will ever have the monument’s 780 acres of undulating grasses to sooth our frayed nerves, but, we can create an eco-friendly part of our landscapes which will echo nature’s prairie glory while providing us with new garden features which require less fertilizer, less water and, hopefully, more enjoyment.

Tall Grasses. Image by pixabay.com

Grasses are adaptable. They tolerate most soil types and are easy to grow additions for a home landscape. From tall and wispy varieties that sway beautifully in the breeze to low-growing grasses which are great for ground covers and turf replacements, your fall and winter landscape can also look more appealing with the added texture and color that ornamental grasses provide (just give them three-years to reach maturity). 

With the minimal maintenance they need, what could be better? And, yes, containers can be used to add even more visual interest. Grow grasses in colorful pots to create seasonal decorations that can be continually reconfigured.

Carex. Image by unquadratodigiardino.it

Low growing ornamental grasses are great for edging, ground covers or container gardens. Sedge is one type of low growing ornamental grass. Blue Sedge ‘Elijah Blue’ (Festuca glauca), for example, is a semi-evergreen example with beautiful, bluish-colored foliage that is also deer resistant. It gets 6 to 12 inches high.

If the look is appealing, but something larger is desired, Blue Oat Grass (Helictotrichon sempervirens) is another popular and larger version. The blue-grey foliage reaches about 3 feet tall with the autumn seed heads topping the plant at some four feet. 

A dwarf fountain grass, 'Hamelin’, (Pennisetum alopecuroides) is another appealing choice of small stature. While standard fountain grasses reach 4 to 5 feet, dwarf varieties only reach 2 to 3 feet. It is gorgeous all year round and makes a real impact on the landscape. 

If a spot of color is also needed in any sunny area, take a look at some non-grass options such as Orange New Zealand Sedge (Carex testacea). It is bright green and gradually turns orange by winter. Fox Red Curly Sedge (Carex buchananii) offers a red-bronze foliage that fades to a golden color at the tips. 

Whether in the ground or in a container, I think my favorite Japanese Sedge (Carex morrowii) for sun or shade is C. ‘Aureo-variegata’ (see above) which I have had in my own yard for 20-years. All offer deer resistance and unique evergreen color and texture, which are added bonuses to suburban and rural dwellers.

Taller ornamental grasses make beautiful, interesting hedges and accent points in the yard. Switchgrass (Panicum virgatum) is a main species from the American prairies and comes in many varieties that turn to reds and oranges in the autumn. 

‘Adagio’ Maiden Grass (Miscanthus sinensis) is another showy choice. Feathery pink-bronze plumes add texture, and the foliage adds lots of autumn and winter colors ranging from golds to oranges to wines. 

Feather Reed Grass such as ‘Karl Foerster’ (Calamagrostis x acutiflora), creates excellent area punctuation points in outdoor vignettes and work well as additions to cut flower arrangements indoors. Outdoors, their summer flowers and feathery stalks that turn to shades of beige and gold in the fall make a brilliant display. 

A favorite tall one for me is Miscanthus sinensis (Maiden Grass) ‘Morning Light’ which has creamy white margins that can lighten darker corners of the garden or form a shimmery five-foot hedge.

Many of these taller deciduous grasses offer four seasons of visual interest. The returning spring will bring with it fresh green upright or cascading foliage. Summer and autumn see increased height with inflorescences that develop into attractive seed heads (great food sources for the birds) and accompany the ever-changing foliage to add more interest in the yard.

To keep the herbaceous ones attractive in the autumn and winter months, wait until early spring to cut them back to 6”, just as the new growth begins to show. If you have an evergreen grass, there is nothing to do. Simple pruners (and a pair of gloves) work well for cutting task. 

If the grasses grow too large for the space allotted to them or start looking bare in the center, it may be time to divide them into three or four pieces. Most fellow gardeners will advise using a shovel to dig and divide the clumps. 

As a lazy gardener, let me suggest using a reciprocating saw (AKA, Sawzall) to divide large clumps of the tall grasses. The process is infinitely quicker and easier on aging backs. Make sure each section of the clump has roots, is replanted in a sunny spot and is well-watered for the next two years.

The other bonuses of ornamental grasses is they rarely have pests with which to contend and they rarely need fertilizer. Most varieties are deer resistant as well. With so much to offer for so little effort, gardeners may have a hard time stopping at one or two varieties. Have fun and experiment with different kinds to see what you like best. Happy Gardening all!

Garden Guy Bruce Bennett

Contributing garden columnist, Bruce Bennett, is a Washington State University Certified Master Gardener, lecturer and Seattle-area garden designer. 

If you have questions concerning this article, have a question about your own landscape or want to suggest a topic for a future column, contact Bruce at gardenguy4u@gmail.com.

See his previous columns here.