There are many varieties of ornamental grasses. Most of them share an important trait: low-maintenance. But learn about the features of each individual type before deciding what you want to buy. The heights and hardiness of the following plants vary greatly:
- Big bluestem
- Maiden grass
- Zebra grass
- Purple silver grass
- Purple fountain grass
- Ornamental millet
- Blue oat grass
- Northern sea oats
- Black mondo
- Blue fescue
- Golden Hakone
- Japanese blood grass
What Makes These Types of Grasses "Ornamental?"
These grass varieties are called "ornamental" for two reasons, both of which are good arguments for including them in your landscaping:
- You don't walk on ornamental grass, so there's no pressing need to maintain it at a certain height.
- A single ornamental grass plant can be quite pretty to look at.
The term, "ornamental," is used to distinguish this type of grass from "lawn" grass. Ornamental grass is very different from the "grass" that many of us have reluctantly been mowing since our childhoods. The latter is a functional grass, serving primarily a practical purpose: It forms a uniform surface on which to walk when we're out in the yard. Ornamental grass, by contrast, isn't meant to be mowed, isn't meant to be uniform, and isn't meant to be tread upon.
In terms of aesthetics, functional grass is mainly negative space. Its job is not so much to be admired, in and of itself, as it is to form a stage on which the yard's actors (flowers, shrubs, trees, hardscape, etc.) play their roles. Ornamental grass, by contrast, is one of the yard's actors. The primary purpose of ornamental grass is to be pretty, to be an "ornament."
Ornamental grass is used in landscape design the way you use flowers, shrubs, and trees. In fact, it's often mixed with such plants to fill flower beds, creating diversity in terms of form and texture. When composing such beds, it's best to layer the plants, placing the tallest in the back, the shortest in the front, and the rest in the middle. For this reason, we need to categorize ornamental grasses in terms of their height, as follows (all should be grown in full sun unless otherwise stated).
Tall Varieties of Ornamental Grasses
No fall or winter landscape should be without a tall ornamental grass. Plumegrass (Erianthus ravennae) is grown in USDA planting zones 4 to 9. It grows 8 to 12 feet tall (its clump has a spread of 3 to 4 feet). This plant, with its tall, thin shafts and fluffy coiffures, has a delicate structure that lends a touch of charm to the harsh winter landscape. Because of its height, a plant such as plumegrass can be used as a focal point.
Andropogon gerardii Indian Warrior is a cultivar of big bluestem grass suitable for zones 3 to 9. A typical clump size is 5 feet tall by 2 feet wide. Starting out green, the leaves turn purple in the middle of the summer. In fall, that color morphs to a reddish-purple. The flower heads are reddish.
Maiden grass (Miscanthus sinensis Gracillimus) is a fine choice in zones 5 to 9 for a tall, drought-tolerant ornamental grass, as it reaches as much as 7 feet in height, with a spread a bit less than that. Maiden grass bears coppery tassels as seed-heads in early fall, eventually turning silvery and adorning the plant as a "plume." Don't cut the clump's stems back until after the bleakness of winter passes, since the graceful stems and puffy plumes provide visual interest on an otherwise barren December-February landscape.
It's mainly late in the season that Miscanthus sinensis Gracillimus provides much of a display (after it blooms). If you're looking for a plant that offers more to look at earlier in the year, try Miscanthus sinensis Zebrinus (zones 5 to 9). The "zebra" markings on its leaves provide plenty of visual interest even before it flowers.
Nor are these the only types of Miscanthus sinensis, a species commonly called "silver grass." Purple silver grass (Miscanthus sinensis Purpurascens) measures 5 feet tall by 3 feet wide and is suited to zones 4 to 9. Its green summer foliage becomes reddish in fall. The seed-heads are mauve-colored.
Medium-Sized Varieties of Ornamental Grasses
Purple fountain (Pennisetum setaceum Rubrum) is a tropical ornamental grass. If you live in an area subject to harsh winters, you'll need to treat it as an annual. The plant reaches a height of 3 to 5 feet, with a spread of 2 to 4 feet. Its purplish flower spikes are followed by fluffy, attractive seed-heads tinged with purple or burgundy. Its spiky foliage is also burgundy.
Another type of Pennisetum treated in the North as an annual is Pennisetum glaucum. A popular cultivar is Purple Majesty. If the common name of "millet" for the species sounds familiar, that's because millet seed is often part of bird-food mixes. Purple Majesty is so called for its very dark foliage and cattail-like seed-heads. It tolerates a little shade, but be sure to grow it in full sun to achieve maximum darkness. It reaches 3 to 5 feet tall.
Blue oat grass is a mounding, cool-season ornamental grass suitable for zones 4 to 8. Known botanically as Helictotrichon sempervirens, deer tend to leave this plant alone. This ornamental grass attains a height of 2 to 3 feet tall, with a similar spread. It tolerates some shade, but grow it in full sun (and a well-drained soil) if you wish to enjoy the signature blue hues of its foliage to the fullest. The plant also produces spiky, dark flowers with a bluish tint in summer that turn harvest gold in autumn.
Northern sea oats (Chasmanthium latifolium) is an ornamental grass that grows 2 to 3 feet high in loose clumps of green foliage. Its name comes from its seed pods, which look like oats. This deer-resistant ornamental grass is cold-hardy to zone 5. Even after its leaves have dried and died, it provides visual interest to the winter landscape.
Short Varieties of Ornamental Grasses
For a shorter deer-resistant plant, try lilyturf (Liriope spicata). Lilyturf (not a true ornamental grass, but a perennial) can be grown in zones 4 to 10 and reaches only about 1 foot in height. Lilyturf likes water but also prefers well-drained soil. Select an area with partial shade and soil rich in compost for best results. This ornamental grass, too, has a spiky flower, ranging in color from white to lavender. In autumn it bears a dark berry. You'll want to contain this plant, however, because it's invasive.
Likewise, black mondo grass (Ophiopogon planiscapus Nigrescens) isn't a true grass, but it functions in landscaping as if it were. Also like liriope, it can be invasive. Black mondo reaches 6 inches in height. The striking color of this zone-6-to-9 plant combines well with plants that bear golden or chartreuse leaves. It can take some shade. Carex Spark Plug is another impostor (it's a type of sedge) that nonetheless plays the "shorty" role well, reaching only about a foot in height. It is a shade plant.
Another short ornamental grass (around 1 foot by 1 foot) grown in zones 4 to 8 is blue fescue (Festuca glauca Elijah Blue). The popularity of this clumping, drought-tolerant ornamental grass lies in the blue color of its foliage, which will beautifully complement any surrounding plants you may have with silvery foliage, such as lamb's ears (Stachys byzantina). The plant resembles a pincushion bristling with blue pins. As with maiden grass, cut back the foliage in early spring. Divide it every few years to rejuvenate it.
If you prefer your blades to be gold-colored, try golden Hakone grass (Hakonechloa macra Aureola). It can be tricky to achieve the best coloration with this plant, but it will often turn a wonderfully warm golden color when grown in shade. It also offers wispy seed-heads in fall that add further interest.
Standing at 12 to 18 inches high at maturity is Japanese blood grass (Imperata cylindrica var. rubra), which can be grown in zones 5 to 9. Plant it in full sun to partial shade in a well-drained soil. Drought-tolerant once established, it bears reddish blades. The species plant is highly invasive, but varieties such as rubra are tamer, although you still must watch out that they don't revert back to the tendencies of their species.
How to Trim Ornamental Grass
Most people understand that ornamental grasses need a good haircut, at some point, after they have turned brown. It's just a question of when.
While tidy folks may prefer to trim ornamental grass at the end of autumn to give the landscape that "clean-cut" look before winter sets in, others prefer to do it in spring. Winter interest is one of the main excuses for growing ornamental grass, and you lose that if you trim in fall. Just make sure that, when spring does come, you cut the plant back early enough to get the old growth out of the way before the new growth emerges. Otherwise, you'll be worried about mistakenly trimming the new shoots, since they'll be right in your way as you attempt to remove dead stalks.
So much for what might be considered the "when" part of the question. But the "how" is worth considering, too to avoid making a mess when you trim ornamental grass. Otherwise, your garden will end up looking like a barber shop floor, after a customer has just left. To avoid this mess, tie the dead stalks up into a bundle before you make your cuts. That way, after the cutting is done, you mainly have just one object to pick up and move, rather than all of the individual stalks.
Low-Care Landscaping With Ornamental Grass and Mulch
Whether you mix ornamental grass with shrubs, trees, and flowers or let it stand alone, you'll want to apply mulch around ornamental grass. Replacing lawn grass with a combination of mulch and ornamental grass can reduce yard maintenance requirements. While this may not be feasible for large areas, it's certainly an option for small plots of land. Remember, maintaining a lawn goes beyond mowing grass. It also includes such tasks as: