Ornamental Grasses: A Unique Landscaping Choice
Why Choose Ornamental Grasses?
Ornamental grasses are a choice in many contemporary landscape designs. Some are planted as bold specimen plants, others arranged in large mass plantings and still others as low growing groundcovers or edgings. Low-maintenance, year-round interest, and fast growth make annual and perennial grasses popular in both commercial and homeowner landscaping.
Many ornamental grasses sport colorful foliage, ranging from almost black, through green, blue-green, gold, red, cream and white. Some are attractively striped or banded. Others are planted primarily for their flower plumes and spikes. Several will provide dramatic and lasting interest through the fall and winter months.
Each contributes to the attractiveness of the garden or landscape in its own unique way. Some are tall, providing shelter and privacy, others provide beautiful accents of feathery plumes. Still others have neat, low-growing clumps.
Because grasses provide movement and texture as well as color, they combine well with other kinds of plants. While large mass plantings are often found in commercial landscapes, the most successful way for home gardeners to use ornamental grasses is to integrate them with perennials, annuals, shrubs, bulbs and evergreens.
Height Can Define Placement
Tall upright grasses create visual linear interest, especially at the back of a border. Many have attractive and bold lines and feathery or plume like seed heads, holding their visual interest throughout the year.
Medium-sized grasses can be massed together, and suitable in a garden designed to be low maintenance. They combine well with spring flowering bulbs or in a border where they can add texture and movement without taking over visually.
Low growing ornamental grasses are ideal for edging around shrubs or combining with spreading evergreens. They can be mass-planted for a low maintenance ground cover or planted in rockeries for textural interest.
Cool Season Grasses
Grasses start their new spring growth depending on temperature.
Cool season grasses start new growth in early spring when both air and soil are still cool. They look best in cooler weather, and may go dormant in hot climates or the dry conditions of summer. Many are evergreen in milder areas, and need only the winter-browned foliage removed in spring.
Most are medium to low sized plants, and mowing them in July will encourage lush regrowth for the fall.
Examples of cool season grasses are the fescues, tufted hair grass (Deschampsia), ribbon grass (Phalaris) and quaking grass (Briza).
Warm Season Grasses
Warm season grasses wait until both the soil and the air are consistently warm before they show new growth. They love hot weather and lots of sun.
Warm season grasses are the stars of late summer and fall. With tall clumps and showy spikes or plumes of flowers, they are the drama queens of the grasses. These grasses are their best in summer, but can add garden interest throughout the winter.
Generally, the foliage will brown in fall, and this dry foliage must be cut back the following spring.
Examples of warm season grasses are Pampas grass (Erianthus), fountain grass (Pennisetum), Japanese silver grass (Miscanthus species) and Japanese blood grass (Imperata).
Understanding Ornamental Grasses
With the increasing popularity and availability of ornamental grasses for landscaping, it is important to have some basic knowledge before you buy. No matter the climate, soil type, space, or position, there is a suitable grass choice.
Before you select and plant any ornamental grass, know its growth habits. Grasses are either clump-forming, rhizome forming or stolon forming.
How Does Your Grass Grow?
Clump forming grasses grow in neat mounds. They will not become invasive, so mix well with perennials. They increase in size over time and will need to be divided so the center of the clump does not die out.
Rhizome forming grasses spread with underground rhizomes, and can be invasive. They need their own space, since they can take over any spot they are planted in.
Stolon forming grasses are similar, but they spread by stems (stolons) running along the surface of the ground that root and form new shoots. Ornamental grasses that spread this way are best located in a contained area so they don’t spread.
As well as becoming familiar with the rooting habit, make sure you select a grass that will fit the available space. Some are low growing and compact, others medium sized and still others are considered tall or large. Each type has its place in the landscape, so become well informed and familiar with their habits before you make your selections.
How to Select Ornamental Grasses
Before you purchase any plant, check its general health. The foliage should be springy, colorful and not too dense. If the plant already shows full dense foliage, that could be a sign that it has become congested in the container and is root bound. It is difficult to establish a root bound plant.
Slip the plant out of the container so you can check its general health, and reject any that are root bound, dried out, or have not yet grown a mature root system. If a plant has been overwatered, the foliage may also show distress. Look for leaves that are dark brown at the base and pull away easily. This is an indication of early rot caused by over watering.
Once you have selected your new ornamental grass plants, make sure the soil is prepared properly. In an ideal situation, you will have deep-tilled the soil the preceding fall, but spring digging and adding organic matter is okay as well.
Grasses do not need a lot of fertilizer, so add just a little general purpose fertilizer or even rely only on the addition of compost. Once established, your ornamental grasses will not need fertilizing.
Spring is the best time to plant ornamental grasses. This gives the plants an entire growing season to develop a good root system before the following winter.
Plant It Right
Thoroughly wet the roots by submerging the new plant, still in its container, into a bucket of water. Once bubbles stop rising, lift it out and let the excess water drain out.
Remove the plant from the container and place it into the hole, firming the soil around it. Do not set the plant deeply, since that will allow it to rot or develop root diseases. Water well, and water regularly to encourage the plant to become established.
Once established, your grasses will need watering only during dry conditions. The amount of water will, of course, depend on the species of grass, the location and the general climate.
How to Maintain Your New Grasses
To control weeds around ornamental grass plants, apply some mulch. This will not only deter weeds, but will retain soil moisture. It will also keep heavy-seeding grasses from re-seeding the area.
Leave your grasses standing over winter. This not only is a way to give interest and texture in the winter garden, but the foliage will help protect the plant's crown from freezing.
In spring, cut back the dry foliage of deciduous grasses to about 4 inches. Do this early, before the new growth starts. Old foliage left on will insulate the crown from the sun's warming rays and delay the new growth.
Most ornamental grasses require little maintenance once established, other than removal of old foliage and seed heads and possible dividing.
Fountain Grass: A Warm Season Ornamental
Fountain grasses (Pennisetum sp.) are among the most popular and attractive ornamental grasses for both home and commercial landscaping. This drought tolerant warm climate grass is native to Africa and parts of western Asia. Pennisetum setaceum has been introduced as an ornamental grass to many parts of the world.
Being a mound or clump forming plant, fountain grass does not become invasive like rhizome-forming grasses. All fountain grasses have densely clumped foliage that arches gracefully and bristly plumes of flowers that range from 3–15 inches long. Most fountain grasses range in height from one to 3 feet, with new varieties that grow to 6 feet.
Unfortunately, because of its fast growth and multitude of wind dispersed seeds, it has become an aggressive and invasive weed in warm dry locations such as Hawaii, California and Arizona.
The Best Climate for Pennisetums
Many Pennisetums are cold hardy to USDA zone 7 and above as perennials. All types do best in a hot and sunny location, with well drained soil, with protection from strong winds. They make a bold statement lining a driveway or walkway or grown in containers. If planted in containers and wintered indoors, fountain grasses can be treated as perennials.
Even in less mild climates, warm season fountain grasses can be ideal annual landscape plants. The attractive fountain like foliage and tan, pink or purple flower plumes can remain in place all winter, although it is best to cut it back in late winter or early spring.
Choose Your Pennisetum Species
P. alopecuroides forms 4 foot clumps of narrow green leaves and buff colored feathery flower spikes and seed heads. The foliage turns a bright almond in fall and early winter. ‘Lumen Gold’ is a patented variety that has bright gold foliage in spring, fading to a soft lemon in summer.
Dwarf varieties 'Hameln' and 'Little Bunny' are excellent for massing, edgings or container growing. 'Moudry' is distinctive for its near-black flower heads. This species is generally hardy in zones 5–9, and is drought tolerant once well established.
P. setaceum ‘Rubrum’ is the purple-leaved fountain grass. With three to four foot burgundy-red foliage and fuzzy rosy-red plumes in late summer and fall, it makes a wonderful accent or specimen plant either in the garden or in containers. It is hardy only in zone 9, so treat it as an annual or plant it in a container and bring it indoors over the winter. Cut it back, to about three inches, and place the container in a cool place until spring weather is warm enough.
'Burgundy Giant' is a newer selection similar to rubrum, but growing up to 6 feet tall. It has wide arching beet-red leaves and rosy-purple plumes. Also hardy only in zone 9, it must be wintered indoors so is best grown in containers or treated as an annual.
P. orientale, or oriental fountain grass, has unusual rose pink flowers that appear much earlier than other Pennisetum species. It is an excellent medium sized grass for borders and massing, and is hardy in zones 7–9.
Although the different species and selections vary in hardiness, most are best treated as annuals in cold areas. Fountain grass is a low maintenance plant that will beautify any landscape or garden.
Choose Miscanthus for a Bold Landscaping Statement
When you are looking for large bold plants, suited to mass plantings, the Miscanthus family of ornamental grasses could easily fit the bill. Native to Japan, China and Korea, they were introduced to North American landscapers over a hundred years ago. The spectacular feathery plumes rise above the clump of leaves which often turns red, orange or bronze in the fall.
These bold ornamental grasses are clump-forming. The flowers of all species and varieties are fan shaped panicles that add an airy graceful touch to the fall borders. Use the flowers to add to your cut bouquets as well.
Growing Tips for Miscanthus
These low maintenance plants will integrate well in a mixed or perennial border. Miscanthus easily tolerates heat, salt, and humidity, so is an extremely good choice for warmer regions or coastal areas. It is hardy in USDA zones 5–9, so can be used extensively in landscaping.
Miscanthus is best planted in spring, but it can be planted in the fall. They prefer well drained but moist soil and full sun, although they will tolerate drier soil once well-established.
The tall stalks which hold the flowers can remain upright over winter, giving your garden and border some interesting highlights in an otherwise barren season. The foliage and plumes should be cut to the ground in late winter, before new growth emerges.
It should be noted that Miscanthus is considered invasive in some areas, so seed heads should be removed to avoid seeds from forming and being spread by wind. Miscanthus requires two different species to develop viable seed, so it is recommended to grow only one species.
The Main Species of Miscanthus
If you are looking for a taller clumping grass to add a striking and bold accent to your gardens, then look no farther than these three Miscanthus species. Many varieties of this ornamental grass are available.
- Miscanthus floridulus: Known as giant Chinese silver grass, this one has tall clumps of green leaves with gracefully arching tips. The strong tall stalks support reddish-pink flower spikes in autumn that open to beige plumes as they mature. Tolerating poor soil and even shade, this 3 metre tall specimen can be used as a screen or living fence.
- Miscanthus sacchariflorus: Giant silver grass quickly forms a patch of tall corn-stalk like stems with graceful arching foliage resembling bamboo. The soft white silvery plumes turn reddish as they mature, and the foliage also turns an interesting red-orange in the fall. The roots or rhizomes of this variety do tend to run, so be careful where you locate it. It is suited to a waterside location as it prefers a rich and moist to wet soil.
- Miscanthus sinensis: Japanese silver grass is the most common Miscanthus, with a superb group of specimens, most ranging 5–6 feet tall. All of them bloom in fall, holding their shape well into winter. The foliage fades into tan and cream shades, so is a nice contrast to winter evergreens.
Popular Miscanthus Sinensis Cultivars
- Zebrinus: Bright green leaves with horizontal bands of yellow make this variety an unusual and attractive specimen. The copper tassels turn to silvery white plumes in the fall. Zebra grass may grow to seven feet tall, spreading 4–6 feet, wide. It is rabbit and deer resistant.
- Variegatus: Variegated silver grass has distinct striped green and white leaves in an arching clump. It has creamy plumes in September, and with a height of 5–6 feet it makes a bold statement.
- Silberfeder: This silvery feather grass is an older variety with tall shimmery white plumes held high above the foliage on tall stems. It needs a lot of room, as the clumps can grow up to 8 feet tall and spread 5 feet wide.
- Purpurascens: Known as flame grass, this ornamental grass has upright clumps of green leaves that turn flame-orange and red in fall. Spikes of rose flowers show in August.
- Gracillimus: This maiden grass has long arching and narrow green leaves that curl towards the tips. It is not a reliable flowering type in cooler areas, but in warm areas it has beautiful soft plumes that change to silver as they mature.
- Morning Light: This variegated maiden grass is similar to Gracillimus, but has a narrow band of white on the leaf margins, giving a silvery shimmering effect. Its late showing flowers are bronze-red spikes.
- Flamingo: The rose-pink plumes of this maiden grass give its name. Like many other Miscanthus varieties, the plumes change to silvery-white as they mature. The narrow arching leaves with white ribs turn orange in the fall.
Choosing What's Compatible With Your Space, Conditions and Style
Ornamental grasses should be chosen by whether they are clumpers or runners, by their mature size, and whether they bloom in the cool or warm season.
After that, it’s a matter of choosing an ornamental grass that’s compatible with your gardening space, growing conditions and gardening style.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Nicolette Goff