Beverly Hoffman

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!

Going en masse

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.

Caution!

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.

Options
If you need a grass for a container, consider Molinia caerulea ‘Variegata,’ a clumper with yellow striped leaves, about 3 feet high. This is one that also can be used as a specimen or planted en masse. An even shorter grass, 18 inches high and wide, is Molinia caerulea ‘Moorflame,’ one of the first to bloom in the spring. Plant it where it can be backlit by the setting sun. It can be cut back in January. I have planted a variety of grasses in pots around our garden, which add texture to the vignette of other plants.
Versatile ornamental grasses dance wildly in the wind. Oh, on such a day, I want to do the same!
 
Reach Beverly Hoffman at columnists@sequimgazette.com.