In our valley, winds swirl across the strait and through the Olympic Mountains, oftentimes playing havoc with our gardens to the point we must either replace plants because of wind damage or avoid choosing them altogether. Ornamental grasses (family Poaceae), however, not only thrive but are at their most spectacular as they arch and sway in air currents.
Another attribute of ornamental grasses is the way the sunlight is reflected in seed heads, especially in the autumn as daylight is waning, and the grasses seem to channel that light, offering a textured luminescence to our gardens. When both the sunlight and the wind are present, ornamental grasses are transformed into a diaphanous dance.
Before moving further into the subject and certain choices of grasses, a caveat: Grasses can be both overused and underused. It’s somewhat like the conundrum of teaching a teenage girl how much lipstick to wear. Too much looks ghastly and too little raises the question of why she bothered to use any at all.
Most grasses are defined as cool season or warm season, certainly an apt consideration in planting. I like to think of them from a different perspective, however. They can be specimen plants, which means they can stand alone in the garden with all other plantings as counterpoints. An example of specimen ornamental grass is Stipa gigante (giant feather grass), a statuesque clumper with evergreen blades 2-3 feet high.
In summer, its sheaves emerge and open so that it is a full 6 feet tall. It definitely is a punctuation mark!
The other way ornamental grasses can be used is in mass plantings, a mini-prairie that exemplifies the line “amber waves of grain … above the fruited plain.” An example of grasses that need to be planted en masse are Nassella (formerly Stipa) tenuissima (Mexican feather grass), threadlike bright leaves about 2 feet tall. It is drought tolerant but can self-sow if watered too frequently; to prevent that, cut plants back before seeds ripen.
Two well-behaved ornamental grasses are Panicum virgatum ‘Rotstrahlbusch’ and ‘Shenandoah,’ both with red tones. ‘Rotstrahlbusch’ is a compact, 3-foot-tall plant and in the summer it’s red, fading to crimson in the fall with burgundy seed heads. It will not self-sow and is an excellent substitute for Japanese blood grass, which can become invasive. It’s fairly drought tolerant. Once its fall color fades, it can be cut to the ground. ‘Shenandoah’ has 4-foot-high leaves that initially are green and then become red-tipped. It, too, gets an A+ in deportment.
Ornamental grasses provide multi-season interest and are fairly low maintenance. Temperature causes ornamental grass to grow. Some prefer the cool weather of early spring and need some water during the warm seasons; if not they turn brown and begin dormancy. Plants in this category are Carex, Hakonechloa, Festuca, etc. Warm season grasses begin to show growth once the ground becomes warm and include Miscanthus, Pennisetum, Muhlenbergia, Panicum, etc.
Be careful not to over-fertilize ornamental grasses; the increased nitrogen can lead to them flopping over. I really don’t fertilize mine at all, except by applying organic mulch, which also prevents seeds from sprouting. Water well the first season and then most are fairly drought tolerant.
Be careful when choosing grasses. Talk to the nursery workers about how grasses grow through underground rhizomes and how water and weather can affect their growth. Are they excessive self-seeders? Miscanthus sinensis (silver grass) was one of the first ornamental grasses to become a rock star several decades ago, especially the cultivar ‘Morning Light,’ but some gardeners have found it, as well as ‘Zebrinus’ and ‘Gracillimus,’ to be invasive.
The Elisabeth Carey Miller Botanical Garden in Seattle has removed Molinia caerulea (moor grass) ‘Bergfreud,’ ‘Fontane,’ ‘Skyracer’, ‘Staefa’, as well as Molininia arundinacea (tall moor grass) ‘Karl Foerster’ and ‘Windspiel’ because they seed too vigorously. Several other grasses to be careful about are Pennisteum ‘Moudry’ (but ‘Hameln’ and ‘National Arboretum’ are both good choices), Phalaris arundinancea (ribbon grass) and Chasmanthium latifolium (river oats).
Besides being used as a specimen plant or en masse, ornamental grasses also can define edges. I have a number of Hakonechloa (Japanese forest grass) along a lower driveway. Some of the taller grasses can become a hedge for privacy. Panicum virgatum ‘Shenandoah’ (mentioned above) works well. It is slow to emerge in the spring, so bulbs planted around it can camouflage the deciduous plant until it decides to grow.
The Tractor Man
Tue, Feb 14, 2012
A shift in our thinking
Tue, Oct 18, 2011
Ornamental grasses dance to their wind song
Thu, Sep 22, 2011
Divide … and have!
Thu, Aug 18, 2011
The low life and high life of a garden
Wed, Jul 20, 2011
Plants, problem solving and personality
Tue, Jun 14, 2011
From the sky: a look at our gardens
Wed, Apr 20, 2011
Time to plant a vegetable garden … with children
Wed, Mar 16, 2011
One New Year’s resolution
Tue, Jan 18, 2011
Blessed by the bounty
Wed, Nov 17, 2010
Diversity creates richness
Tue, Oct 19, 2010
The ruffled ladies
Wed, Sep 15, 2010
Wed, Aug 18, 2010
Keeping birds safe in our gardens
Wed, Aug 11, 2010
Living respectfully on the land
Wed, Jun 30, 2010
Prune, don't ruin, those shrubs and trees
Wed, May 26, 2010
Undoing deer's damage with new shrubbery
Wed, Apr 28, 2010
Treat water as our most precious gift
Wed, Mar 10, 2010
Northwest native mock orange makes good scents
Wed, Feb 3, 2010
Planting perennial blessings
Wed, Jan 6, 2010