Ornamental Grasses – Low Maintenance/ High Drama by Brian Oleksak, County College of Morris
Mexican Feather Grass and Vervain
One of the most exciting trends in landscape horticulture in the past few years has been the rediscovery and new introductions of ornamental grasses in the marketplace. The old standards of fountain grass, feather reed and Chinese silver grass still play a role in designs, but the palette is much broader now for creative designers. The desire for a greater use of native species, curbing the spread of invasive plants and the inspirational designs by European visionaries who recognized the natural beauty of North America launched an aesthetic trend that is changing the industry. Grasses are members of the Poaceae family, a family of monocots with a worldwide distribution. From a horticultural perspective, we tend to group the various genera as cool season and warm season in their seasonal performance. As the name implies, cool season grasses are physiologically active and growing during cooler seasons, particularly the spring and fall. Warm season species, like switch grass, blue grama and prairie dropseed, are most active during the heat of the summer and actually emerge in the springtime three to four weeks after their cool season counterparts. Landscape maintenance professionals should be aware of this growth habit as the customer may assume that the grasses did not overwinter. Simply assure the customer
that these species will reemerge when soil temperatures get warmer. One of the best arguments for including ornamental grasses into a landscape design is the ease of care and maintenance. When considering the selection of any landscape plant we should always ask “Where is the plant found in nature?” Selecting the right plant for the right place always takes into consideration the plant’s evolutionary history and adaptation to its environment. Grasses evolved on prairies and open grasslands in full sunlight, frequently undergoing periods of droughty conditions. When used in residential and commercial designs grasses require full sun and welldrained soil conditions for best performance. Few grass species tolerate shaded locations; the exceptions being Japanese forest grass (Hakonechloa macra) and Northern sea oats (Chasmantium latifolium) which will tolerate semishaded conditions. Designers seeking a grassy look for shaded locations should instead explore the possibilities of using sedges (Carex species) of which there is a vast array of new introductions on the market. Landscapers should avoid supplemental irrigation and excessive fertilizer as these practices may encourage overly lush growth and weak stem strength causing the grasses to flop over after a heavy rain. Yearly maintenance of ornamental
grasses is minimal, making them perfect candidates for use in commercial designs and sprawling housing developments. Grasses need to be cut back once per year to remove last year’s display and allow for the emergence of the current season’s growth. The landscape maintenance professionals and their clients can work out the details as to when this happens. Some people prefer to leave the grasses standing for the winter to provide interest in an otherwise barren landscape. For these clients cutting back grasses is part of the spring cleanup regime. Some professionals prefer to cut them back in the fall in anticipation of heavy snowfall and winter maintenance activities. Either practice is acceptable as it will not affect the growth of the grasses in the future. Grasses are a perennial feature of the landscape and require little care beyond seasonal cutbacks. However, after several years on the site you may discover a dead zone originating in the center of an established grass clump. Should this happen you should dig up the clump, cut out the dead area, divide the vigorous portions and replant them. As features in a design grasses offer many possibilities for softening hardscape elements, blending with the existing environment, reintroducing native species and creating a sense of rhythm and movement with their soft,
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