Switchgrass (Panicum virgatum) is a tall native North American prairie grass that is grown as food for cattle and is commonly used as ornamental grass in garden spaces. As a warm-season grass, you won't see new growth until the late spring, but it provides interest through most of the year. The small, teardrop-shaped flower seeds that appear in the summer have a pink/purple tinge, and the green foliage can feature shades of red. It also turns to shades of yellow in the fall. The stalks and plumes lighten further in the winter and tend to remain upright unless there's heavy rain or snow.
With its spreading rhizomatous roots and clump-forming habit, switchgrass is ideal for use in sloped areas prone to erosion.
|Botanical Name||Panicum virgatum|
|Common Name||Switchgrass, Tall Panic Grass|
|Mature Size||Up to 6 ft. tall|
|Sun Exposure||Full, partial|
|Soil Type||Sandy, clay, moist|
|Soil pH||Acidic, neutral, alkaline|
|Hardiness Zones||3, 4, 5, 6, 7, 8, 9|
|Native Area||North America|
Although switchgrass benefits from plenty of sun, it can adapt to a wide range of temperatures and soil conditions and is very low maintenance. It's also resistant to disease and not bothered by pests.
Not as prolific as some ornamental grass varieties, if the conditions are optimal, it can still spread rapidly. Care should be taken when using it in small garden spaces.
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.
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.
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, and this is why it's sometimes used in boggy areas around ponds.
Temperature and Humidity
Tolerant of a wide range of weather conditions, this grass variety can cope with intense summer heat and freezing winter conditions.
Once established, rhizomatous switchgrass rarely needs additional feeding with a fertilizer. Too many nutrients can cause the grass stalks to droop.
Types of Switchgrass
There are a wide variety of switchgrass cultivars. Some ornamental cultivars can be more sensitive to their environments than others, so it's important to check their needs before planting. Some of the most popular or unique include:
- ‘Blue Tower’ – a very tall cultivar, with distinct bluey-green foliage, that can grow to reach 8 feet in height.
- ‘Dallas Blues’ – with wider blue leaves than most switchgrass varieties, it forms in very dense clumps. It's also known for being particularly drought-tolerant and producing copper color in the fall season.
- 'Shenandoah' - this is one of the smallest switchgrass cultivars, and it only reaches around 2 to 3 feet in height.
- 'Cloud Nine' - the dark blue leaves turn gold during the fall season.
- 'Prairie Fire' - 5-foot leaves turn deep red in summer, and then yellow in the fall.
Cutting back the foliage heavily in late winter or early spring is recommended to encourage healthy new growth.
Switchgrass can easily be propagated through the division of clumps. It's best to do this in the spring as they need warm soil to establish. Clump division is recommended every few years, as the center of the clumps can begin to die out, and this will help to boost their vigor.
How to Grow Switchgrass From Seed
Although switchgrass can grow easily from seeds, it's worth noting that the seedlings often differ significantly from the original plants. If you want to replicate the shades and height of the plants you already have in your garden, it is better to divide the clumps instead.
Seeds need plenty of light, moisture, and warm conditions to germinate. Seedlings form quickly—usually within a few weeks. They take hold quite easily, so starting them indoors in typical potting soil and giving them ample light from a sunny windowsill and regular watering is enough to give them a good start. When starting seeds outdoors in the soil, make sure they are in full sun and keep the ground moist.
No special care is needed for overwintering switchgrass, as it is quite cold-hardy and can handle the freezing temperatures.
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 with Switchgrass
Switchgrass is a potential vector for the Japanese beetle and spotting wing Drosophila, both of 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.
Why is my switchgrass falling over?
Some varieties of this grass don't have the supportive stems necessary to support their height. In this case, staking the grass is a good idea.
Can switchgrass grow indoors?
While it's easy to start switchgrass indoors and keep it inside until the seedlings are hardy enough for outdoor planting, keeping it as an indoor plant is difficult.
What are good companion plants to switchgrass?
Many low, spreading flowers look gorgeous with switchgrass, including phlox, sedums, asters, smoke bush, and red shrub roses.