Ornamental Grasses — A Few Thoughts

Here is a trivia question to share with friends at dinner. What is the most popular horticultural plant in the world? People will respond with maple trees, impatiens, carnations or marijuana, but the answer is turfgrass. It could be fescue or bluegrass, but the number of seeds or pieces of sod sold outpaces other groups of ornamentals. In grasses, turfgrass has been king for centuries, and our ornamental grasses have only been used for a relatively short period of time. They are teens in the world of grass.

Like teens, they can be wild or well-behaved, messy or neat, but they are always changing. Ornamental grasses have been a mainstay in European gardens for many decades. However, the work of Wolfgang Oehme and James van Sweden in the 1980s has been credited in “The New American Garden” style, which incorporates free-flowing design, and in doing so, the lavish use of ornamental grasses. The rush to low-maintenance gardens and landscapes only enhanced their appeal. Since then, grasses have been embraced by growers, landscape architects and retailers, and are an important component in wholesale and retail sales.

The explosion of grasses started with the now ubiquitous Japanese miscanthus grass and has seen the introduction of fountain grass (pennisetum), feather reed grass (calamagrostis), Japanese forest grass (hakonechloa) and numerous others. In the last 20 years, a reasonably passionate love affair with native grasses took hold and the new top guns are switchgrass (panicum) and the blue stems (andropogon and schizachyrium), among others. Every year new grasses are introduced, each one better than the one before it.

Avoid, Be Careful Of And Enjoy These Perennial Grasses

Here are my thoughts on a few perennial grasses. Apologies in advance if I left out some of your favorites.

Avoid. Even though Northern Sea Oats (chasmanthium) is a native, it is aggressive, almost to the point of invasiveness. It is beautiful for the first few years, with handsome foliage, flowers and fruit, but then shows its true reseeding colors. Not on my low maintenance list.

Be careful. Perennial fountain grasses (Pennisetum alopecuroides) like ‘Moudry’ and ‘Hameln’ are dwarf and colorful, many reports show they can also escape, mainly through reseeding. Do not worry about planting popular cultivars of annual fountain grass such as ‘Rubrum’ and ‘Fireworks.’

All cultivars of miscanthus grass seem to have been unfairly painted with the “invasive” brush. However, be sure to check the invasive plant list in your state before installing. In some states, the species and early flowering, older cultivars may well be guilty, but newer introductions and later flowering cultivars do not seed or do not set seed before winter. I suggest asking your miscanthus supplier for a listing of non-invasive selections. Most specialty grass growers have one.

Popular. Switchgrass (panicum) has ridden the native plant movement, and all sorts of excellent nativars are available. If working with any government agency, be it federal, state or local, native grasses will be front and center. My favorites are still ‘Northwind’ and ‘Cape Breeze.’

Blue grasses include big blue stem (andropogon) and little blue stem (schizachyrium). They are native, so they’re useful for publicly funded projects, as well. Many new nativars are on the market, most of the big blue stems are tall and are grown for stature and good fall color. The little blue stems tend to be dwarf in stature but also provide handsome flowering and reasonably good fall color. ‘The Blues’ is still popular, but I also like ‘Prairie Blues,’ ‘Blaze’ and ‘Standing Ovation.’

Specifics. Japanese forest grass, hakone grass (hakonechloa) is probably the best grass for shaded, cool climates. It is a poor choice for warm climates, but in Zone 6 and north, it is quite spectacular where shade precludes other choices. ‘Allgold’ and ‘Aureola’ are excellent choices.

Muhly grass (Muhlenbergia capillaris) is truly spectacular for warm climates, Zone 7 and south. The long plumes of usually pink flowers are traffic stoppers in the fall. The species is wonderful, but I also like ‘White Cloud’ and the earlier flowering ‘Fast Forward.’