Big Bluestem (Andropogon gerardii) is a tall perennial grass native to North America that once dominated the prairie of the American Midwest. Its foliage changes color seasonally, and it is used as an ornamental grass and to rehabilitate prairie land.
I. Appearance and Characteristics
Andropogon gerardi, commonly known as big bluestem, is a species of tall grass native to much of the Great Plains and grassland regions of central and eastern North America. It is also known as tall bluestem, bluejoint, and turkeyfoot.
Andropogon gerardi was formally named in 1792 by Fulgenzio Vitman. It was named for French botanist Louis Gérard, who had first described the plant from specimens that had been cultivated in Provence, France.
Andropogon gerardi is the state grass of Illinois and Missouri and the official prairie grass of Manitoba.
Big bluestem is a perennial warm-season bunchgrass. It is tolerant of a wide range of soil conditions. The main roots are 6–10 ft (1.8–3.0 m) deep, and the plants send out strong, tough rhizomes, so it forms a very strong sod. Depending on soil and moisture conditions, it grows to a height of 1–3 m (3.3–9.8 ft). The stem base turns blue or purple as it matures.
Big bluestem blooms in the summer and seeds into the fall. The inflorescence (cluster of flowers) is a raceme of two to six, most commonly three, narrow spike-like racemes alternately arranged along the top of the stem. It somewhat resembles a wild turkey’s foot. Each raceme contains pairs of spikelets. Each pair has a stalked spikelet with another stalkless spikelet at the base of the stalk. The stalkless spikelet usually has a fertile, perfect floret (with both female and male parts) and an awn (bristle), and the stalked spikelet is awnless, and is sterile or has a staminate (male) flower.
Big bluestem is a mid-successional grass in prairie and other grassland ecosystems. It grows in tall, dense stands that can outcompete other plant species. The stands grow until disturbance interrupts their spread. It is shade intolerant and is adapted to fire.
It is a host to larvae of several species of butterflies, including the arogos skipper, byssus skipper, cobweb skipper, common wood nymph, Delaware skipper, and dusted skipper.
The larvae of the leaf beetle Diabrotica cristata feed on the roots and the adults visit the flowers of other species of prairie flowers. Many ants decorate their nests with the seeds, including Formica glacialis, F. montana, and F. subsericea. Several species of ants, such as F. glacialis, F. montana, F. subsericea, Lasius minutus, and L. umbratus build nests around the base of this bunchgrass, forming large soil mounds.
II. How to Grow and Care
Sunlight
Big bluestem grows best in full sun but is adaptable to part shade. This ornamental grass cannot tolerate full shade conditions.
Temperature and Humidity
As a warm-season grass, big bluestem grows best in temperate climates with warm summers and cool winters. It thrives in the summer months and grows best in temperatures between 80 and 90 degrees Fahrenheit. Big bluestem is well adapted to fire and can recover easily from wildfires thanks to the fact that it spreads via rhizomes.
Watering
Established big bluestem grasses are known for being exceptionally drought-tolerant, and big bluestem is even cultivated and sold by specialty nurseries for this feature. As with most seedlings and young plants, big bluestem will require more frequent watering until it has matured.
Soil
Big bluestem is found growing in the dry soils of the North American prairies. It is highly adaptable to a range of soil conditions, from sandy soils to clay soils, as long as they are well-draining. Big bluestem also grows well in less-than-ideal soil conditions and can tolerate poor quality soils, soils with a low pH (4.8 to 6.9) , and shallow soils. This grass cannot tolerate highly alkaline soils or highly compacted soils that are not well-draining.
Fertilizing
Big bluestem does not require regular fertilization and is well-adapted to grow in poor soil conditions. However, applying a nitrogen-rich fertilizer in the spring months can help big bluestem to establish more quickly, which is especially desirable when it’s grown as forage for cattle or other herds. When grown as an ornamental grass, fertilizing is an optional step but certainly not required.
Pruning
The best way to prune a big bluestem is to cut back shaggy, old growth in early spring, readying it for warmer weather. Use clean, sharp gardening shears.
Propagation
Big bluestem can be propagated through division. As a general rule, wait until the grass is mature and established before attempting to divide.
- In the early spring, as the grass is coming out of dormancy, dig out the roots. Depending on how mature the grass is, the cluster of rhizomes can be very difficult to separate and you may need to use a saw or sharp spade to divide them.
- Cut the clump into sections using a shovel, saw, or knife.
- Replant the sections at the same depth as the original plant. Keep any newly transplanted grasses consistently moist until they have re-established.
How to Grow from Seed
Big bluestem readily produces seeds every year, which can be harvested and planted the following spring. Alternatively, big bluestem seeds can be bought from most garden centers and specialty nurseries.
- For improved germination, stratify the seeds for one month before sowing to help break the dormancy cycle.
- Seeds can be started indoors or sown directly in the garden in late winter or early spring. Sow the seeds at 1/4- to 1/2-inch deep.
- Keep the seeds consistently moist until they sprout. Be patient, as big bluestem seeds can take up to four weeks to germinate.
Potting and Repotting
You can grow big bluestem in pots but it is not ideal because the grass gets tall and wide and topples over easily. The larger the container, the better. Eventually the grass will fill even a large container but you can also plant 2 to 3 grasses together in a large planter that is at least 2 to 3 feet wide and 2 feet deep.
Although big bluestem is winter-hardy, the roots of potted plants are exposed to the cold, unlike in garden soil, so in areas with subzero winters, you need to winterize the container by providing some sort of insulation for the roots.
Overwintering
Big bluestem is well adapted to climates with cold winters and needs no winter protection.
Pests and Diseases
Big bluestem has no serious pest or disease problems.
III. Types of Big Bluestem
- ‘Bison’ has increased cold tolerance and is great for northern climates.
- ‘El Dorado’ and ‘Earl’ work well as forage grasses.
- ‘Kaw’, ‘Niagara’, and ‘Roundtree’ are used for game bird cover and to improve native planting sites.
IV. Uses and Benefits
The grass and its variants are good forage for horses and cattle, and can also be cut and used for hay. The grass is high in protein. While not considered the highest quality native forage found in the United States, it has long been considered a desirable and ecologically important grass by cattle ranchers and rangeland ecologists.
Big bluestem is cultivated by specialty plant nurseries for its drought tolerance and native status. It is often grown for wildlife gardens, natural landscaping, and grassland habitat restoration projects.
Due to its high biomass, big bluestem is being considered as a potential feedstock for ethanol production.
Find Where to Buy the Best Big Bluestem (Andropogon gerardii)
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