One welcome trend that has captured the interest and imagination of neighborhood gardeners in the past 2 decades is the use of ornamental grasses in place of high-maintenance shrubs. Ornamental grasses offer many benefits for a small investment of money, time, and maintenance. Most all grasses require little or no care once established – just a “haircut” once a year in early spring (and not all grasses require this). Cultural needs cover a wide range: some need no supplemental water, some thrive in bogs, and many will grow equally well in sandy or clay soils. Grasses can be grown in conditions as varied as deep shade to full sun; in containers or in a rock garden. Few need compost or fertilizer; grasses are adapted to a lean life. Of the 26 species of grasses I grow (from 20 genera), only one seems to want compost or fertilizer – Imperata cylindrical – and during those summers when I am too busy to tend to it, I am still rewarded with its beautiful show of brilliant red as summer ends and fall arrives.
One note of caution, however; some grasses will become invasive if given the chance. This depends upon region, of course, so a little research should be done before deciding on the plant for your garden. In the Northwest, two grasses that can be rampant spreaders are Nassella tenuissima, Mexican Feather Grass, and Phalaris arundinacea, Ribbon Grass or Reed Canary Grass. In my garden, Mexican Feather Grass has spread via seedlings faster than I can hunt them down and pull them up. As much as I love this grass, I am still pulling out seedlings seven years after planting just two specimens. On the positive side, this grass is always available in my garden, in various stages of growth, so it is one plant I no longer need to purchase.
Phalaris arundinacea, Ribbon Grass, will take as much space as it can find regardless of what else is growing nearby. As stated before, research and careful planning can alleviate potential problems with plants that can become invasive over time. This is a plant that needs to be contained! (My experience as a Forest Steward in a city park has shown first-hand the damage just a few invasive plants can cause in an environment where they have not adapted with controls on their growth. In this part of the country, English ivy (Hedera helix), English holly (Ilex aquifolium), Himalayan blackberry (Rubus armeniacus), and Butterfly bush (Buddleja davidii) are rampant growers and have displaced and/or shaded out countless native plants.)
For versatility, Carex is the group to choose from. Not true grasses but sedges, Carex is a large genus that contains over 1,000 species – from water-lovers to the drought-tolerant, ground covers to giants over 6 feet in height, must-haves for container gardening to stand-alone specimen plants. If you choose only one grass or grass-like plant for your garden, a Carex is an excellent choice. Of special note are C. testacea, C. buchananii, C. eleta ‘Aurea’, C. mertensii, and C. douglasii.
For outstanding accent plants, blue grasses are at the top of the list. Their color complements every shade of green; harmonizes with yellows and reds; the thin blades contrast dramatically with the wide variety of foliage shapes found among perennials and shrubs; and the plants hold up well in winter. Blue grasses work well in any style of garden: from formal to casual, rock gardens to perennial borders, Japanese-style to English cottage gardens. Three of my favorite blue grasses are: Festuca glauca, Blue Fescue, Helictrotrichon sempervirens, Blue Oat Grass, and Leymus arenarius, Blue Lyme Grass.
To add a delicate look to your garden, Miscanthus sinensis, Morning Light, Deschampsia caepitosa, Northern Lights, and Molinia caerulea, Purple Moor Grass are good choices. Finely textured and graceful in movement, these grasses bring an ethereal quality to the garden that few other plants offer. When partnered with dwarf conifers and evergreen perennials, they create a beautiful and unique landscape.
For dramatic color, Ophiopogon planiscapus ‘Nigrescens’, Black Mondo Grass or Imperata cylindrical, Japanese Blood Grass, are outstanding selections. I use Black Mondo Grass as an edging plant that I weave between perennials of much lighter foliage color (it pairs well with Heuchera ‘Lime Rickey’). Japanese Blood Grass is very effective planted in mass or as a specimen plant where it will be back-lit by early evening light and the colors of sunset.
To add fall color to your garden, Panicum virgatum, Shenandoah, and Schizachyrium scoparium, Little Blue Stem, can’t be matched. In early fall, Shenandoah grass is such a strong presence that it outshines all other plants around it.
Little Blue Stem brings a complex array of purples and silvers to the garden that no other grass offers. Both grasses are outstanding in rock gardens and require no special treatment.
Panicum virgatum, Shenandoah Andropogon gerardi, Big Bluestem