Switchgrass (Panicum virgatum) is an upright prairie grass that produces feathery delicate flowers from July to September. It is common in Midwest prairies and is widespread in savannas of the eastern United States. There are several switchgrass varieties to choose from and its high tolerance for different planting sites makes ornamental switchgrass a great choice for any landscape. Providing height, flow, and drama, planting switchgrass brings it all to the decorative garden.
| Common name | Panic Grass, Panic Grasses, Switchgrass, Switch Grass, Tall Panic Grass, Thatchgrass, Wild Redtop |
| Botanical name | Panicum virgatum |
| Family | Poaceae |
| Species | virgatum |
| Origin | North America |
| Life cycle | Perennial |
| Plant type | Herbaceous Perennial |
| Hardiness zone | 5, 6, 7, 8, 9 |
| Sunlight | Full Sun |
| Maintenance | Low |
| Soil condition | Clay |
| Drainage | Moist but Well-Drained |
| Growth rate | Medium |
| Spacing | 3 ft. – 6 ft. |
| Harvest time | Fall |
| Flowering period | Fall |
| Height | 3 ft. – 7 ft. |
| Width | 3 ft. – 7 ft. |
| Flower color | Gold, Yellow |
| Leaf color | Blue |
| Fruit color | Cream, Tan |
| Stem color | Green |
| Fruit type | Caryopsis |
| Fruit benefit | Edible |
| Leaf benefit | Long-lasting |
| Flower benefit | Good Cut |
| Garden style | Butterfly Garden |
| Uses | Container |
I. Appearance and Characteristics
Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico. Switchgrass is one of the dominant species of the central North American tallgrass prairie and can be found in remnant prairies, in native grass pastures, and naturalized along roadsides.
Other common names for switchgrass include tall panic grass, Wobsqua grass, blackbent, tall prairiegrass, wild redtop, thatchgrass, and Virginia switchgrass.
Switchgrass is a hardy, deep-rooted, perennial rhizomatous grass that begins growth in late spring. It can grow up to 2.7 m (8 ft 10 in) high, but is typically shorter than big bluestem grass or indiangrass.
The leaves are 30–90 cm (12–35 in) long, with a prominent midrib. Switchgrass uses C4 carbon fixation, giving it an advantage in conditions of drought and high temperature. Its flowers have a well-developed panicle, often up to 60 cm (24 in) long, and it bears a good crop of seeds.
The seeds are 3–6 mm (1⁄8–1⁄4 in) long and up to 1.5 mm (1⁄16 in) wide, and are developed from a single-flowered spikelet. Both glumes are present and well developed. When ripe, the seeds sometimes take on a pink or dull-purple tinge, and turn golden brown with the foliage of the plant in the fall. Switchgrass is both a perennial and self-seeding crop, which means farmers do not have to plant and reseed after annual harvesting.
Once established, a switchgrass stand can survive for ten years or longer. Unlike corn, switchgrass can grow on marginal lands and requires relatively modest levels of chemical fertilizers. Overall, it is considered a resource-efficient, low-input crop for producing bioenergy from farmland.
II. How to Grow and Care
Sunlight
Switchgrass prefers a full sun position. This will ensure vigorous growth, tall and upright stalks, and the most interesting color. It can handle part shade but be prepared for the stalks to droop and the clumps to be less tightly formed.
Temperature and Humidity
Tolerant of a wide range of weather conditions, this grass variety can cope with intense summer heat and freezing winter conditions.
Watering
A drought-tolerant species, switchgrass can handle dry and hot conditions well. For best growth, though, it prefers to be kept moist. It can even handle light flooding; sometimes it’s used successfully in boggy areas around ponds.
Soil
Part of the appeal of switchgrass is that it can tolerate being planted in most soil types. It does, however, prefer a moist sandy or clay variety. Be aware that if the soil is overly rich, this could result in the stalks flopping, and you may need to stake them up.
Fertilizing
Once established, rhizomatous switchgrass rarely needs additional feeding with a fertilizer. Too many nutrients can cause the grass stalks to droop.
Planting Instructions
Loosen soil in the planting area. Allow enough room for the deep root system to develop.
Dig a hole twice as wide and deep as the root ball. Remove plant from the nursery container and loosen roots if potbound. Place in the hole so the top of the root ball is level with the surrounding soil. Fill in the hole with soil, tamp down gently to remove air pockets, and water thoroughly. Water regularly until established.
Pruning
Cut the foliage to a few inches above the ground in late winter or early spring (after the first growing season) to encourage healthy new growth.
Propagation
Although switchgrass can grow quickly from seeds harvested from your mature grass, seedlings may differ significantly from the original plants. To replicate the shades and height of the plants you already have in your garden, divide the clumps instead.
Division is best done in the late spring as the roots need warm soil to establish. Clump division is recommended every few years, as the center of the clumps begin to die out, which will help boost their vigor.
Here’s how to divide switchgrass:
Depending on the clump size you want to grow, you’ll need a sharp knife or a shovel. You may also need a pot with fresh potting soil.
If you want to grow a small cluster, carefully dig out a stem with its roots intact from the outside of a clump using a knife. Transplantation from a clump into a pot kept indoors can be done any time of the year.
Plant it in a pot, let it grow for a year, and transplant it outdoors in a full-sun location.
To grow a larger clump, dig up the entire clump using a shovel. Dig down with your shovel, in a circle, around the clump to uproot the whole clump.
Divide the clump in fourths using the shovel end and replant it in a favorable location. This should only be done in the spring since this is an intrusive method that can stress the plant. Springtime is a time of active growth, and recovery is most likely.
How to Grow from Seed
Seeds need plenty of light, moisture, and warm conditions to germinate. Seedlings form quickly—usually within a few weeks. They take hold easily, so start them indoors in typical potting soil and give them ample light from a sunny windowsill. Regular watering is enough to give them a good start. However, this plant takes time for its rhizomes to establish.
- Sow seeds in the spring after the soil temperature reaches 55 F.
- Make sure it’s in a full sun location and moisten the ground.
- Plant on a firm, well-prepared seedbed at 1/2- to 3/4-inch depth.
- Keep the soil moist to encourage vigorous growth.
Potting and Repotting
Switchgrass can be started in a pot or grown in a container for about a year as its rooting structures develop and establish. It has a long taproot that will grow 10 feet long or more. It is not the best plant for continued growth in a pot, although mature specimens can be grown in large, heavy, deep pots. When potting, you must also give the grass more water than ground planted specimens.
It can be transplanted successfully from a pot without too much stress outdoors in the spring when the soil temperature has warmed to at least 55 F.
Overwintering
No special care is needed for overwintering switchgrass. It is cold-hardy to USDA zone 3, which includes places like northern Minnesota, Wisconsin, North Dakota, and Maine. It can withstand temperatures as low as -40 to -30 F. It grows year after year, returning in the spring when soil temperatures warm up.
Pests and Diseases
Common Pests and Plant Diseases
Switchgrass is strongly resistant to pests; the ones that do affect the grass from time to time, such as aphids, don’t often cause serious damage.
Fungal diseases, however, are much more common. These might include rust, leaf spot, and smut. A fungicide can be beneficial in keeping large-scale problems with fungal diseases at bay.
Common Problems
Switchgrass is a potential vector for the Japanese beetle and Spotted wing drosophila, which can wreak havoc on commercial crops, especially fruits. Switchgrass planted near large farms can be a potential problem, so keep the location of your garden and landscape design in mind when you plant switchgrass.
- Not Growing or Emerging
Switchgrass is a warm-season grass that thrives in the heat of summer and goes dormant in the cold winters. The soil must be at least 55 degrees Fahrenheit or warmer to germinate or grow.
- Yellowing Leaves
Frequent, heavy rain or overwatering can lead to yellowing. If you see the grass turning yellow, cut back on watering. Another potential cause of yellowing is nutritional imbalances. Check your pH levels; also, the fertilizer salts might be off-kilter. Yellowing can often turn around with a liquid feed of fertilizer 10-10-20 that contains iron.
- Floppy Grass
If your switchgrass is growing well but then starts to get floppy or fall flat, ensure it has full sun. It tends to get floppy in a shady location or if it gets too much fertilizer.
III. Uses and Benefits
- Moth host plant
It is the preferred larval host plant of Dargida rubripennis. It is also a larval host for the Delaware skipper and the Hobomok skipper.
- Biodegradable plastics production
In a novel application, US scientists have genetically modified switchgrass to enable it to produce polyhydroxybutyrate, which accumulates in beadlike granules within the plant’s cells. In preliminary tests, the dry weight of a plants leaves were shown to comprise up to 3.7% of the polymer. Such low accumulation rates do not, as of 2009, allow for commercial use of switchgrass as a biosource.
- Soil conservation
Switchgrass is useful for soil conservation and amendment, particularly in the United States and Canada, where switchgrass is endemic. Switchgrass has a deep fibrous root system – nearly as deep as the plant is tall. Since it, along with other native grasses and forbs, once covered the plains of the United States that are now the Corn Belt, the effects of the past switchgrass habitat have been beneficial, lending to the fertile farmland that exists today. The deep fibrous root systems of switchgrass left a deep rich layer of organic matter in the soils of the Midwest, making those mollisol soils some of the most productive in the world. By returning switchgrass and other perennial prairie grasses as an agricultural crop, many marginal soils may benefit from increased levels of organic material, permeability, and fertility, due to the grass’s deep root system.
Soil erosion, both from wind and water, is of great concern in regions where switchgrass grows. Due to its height, switchgrass can form an effective wind erosion barrier. Its root system, also, is excellent for holding soil in place, which helps prevent erosion from flooding and runoff. Some highway departments (for example, KDOT) have used switchgrass in their seed mixes when re-establishing growth along roadways. It can also be used on strip mine sites, dikes, and pond dams. Conservation districts in many parts of the United States use it to control erosion in grass waterways because of its ability to anchor soils while providing habitat for wildlife.
- Forages and grazing
Switchgrass is an excellent forage for cattle; however, it has shown toxicity in horses, sheep, and goats through chemical compounds known as saponins, which cause photosensitivity and liver damage in these animals. Researchers are continuing to learn more about the specific conditions under which switchgrass causes harm to these species, but until more is discovered, it is recommended switchgrass not be fed to them. For cattle, however, it can be fed as hay, or grazed.
Grazing switchgrass calls for watchful management practices to ensure survival of the stand. It is recommended that grazing begin when the plants are about 50 cm tall, and that grazing be discontinued when the plants have been eaten down to about 25 cm, and to rest the pasture 30 – 45 days between grazing periods. Switchgrass becomes stemmy and unpalatable as it matures, but during the target grazing period, it is a favorable forage with a relative feed value (RFV) of 90-104.
The grass’s upright growth pattern places its growing point off the soil surface onto its stem, so leaving 25 cm of stubble is important for regrowth. When harvesting switchgrass for hay, the first cutting occurs at the late boot stage – around mid-June. This should allow for a second cutting in mid-August, leaving enough regrowth to survive the winter.
- Game cover
Switchgrass is well known among wildlife conservationists as good forage and habitat for upland game bird species, such as pheasant, quail, grouse, and wild turkey, and song birds, with its plentiful small seeds and tall cover. A study published in 2015 has shown that switchgrass, when grown in a traditional monoculture, has an adverse impact on some wildlife. Depending on how thickly switchgrass is planted, and what it is partnered with, it also offers excellent forage and cover for other wildlife across the country.
For those producers who have switchgrass stands on their farm, it is considered an environmental and aesthetic benefit due to the abundance of wildlife attracted by the switchgrass stands. Some members of Prairie Lands Bio-Products, Inc. in Iowa have even turned this benefit into a profitable business by leasing their switchgrass land for hunting during the proper seasons.
The benefits to wildlife can be extended even in large-scale agriculture through the process of strip harvesting, as recommended by The Wildlife Society, which suggests that rather than harvesting an entire field at once, strip harvesting could be practiced so that the entire habitat is not removed, thereby protecting the wildlife inhabiting the switchgrass.
Find Where to Buy the Best Switch Grass (Panicum virgatum)
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