Big bluestem — a towering perennial grass that can reach over 10 feet in height — is an instantly noticeable feature wherever it grows. Named Andropogon gerardi in 1792 after renowned botanist Louis Gerard, this ornamental species is native to the North American Great Plains.
It's a staple in the prairies, helping transform the region's landscape over millennia. Switching shades from blueish green to tan to brown throughout the growing season, big bluestem is also a striking selection in gardens across the country.
Big bluestem is reserved for the outdoors, and you'll need ample growing space for these hardy grasses. Each plant extends six to ten feet in height with thick, expansive roots that can grow six to ten feet deep. Experts recommend stratifying seeds prior to sowing to end the dormancy cycle, and this process is easy to handle at home.
Place seeds in moistened paper towels and enclose them in a container or sealed plastic bag, then let them sit for a month until they've successfully soaked in those damp, warm conditions. Stratification gives the germination process a boost, so your seeds will be ready for sowing come early spring. Sow seeds outdoors about 1/4 to 1/2-inch deep and two to three feet apart, and watch germination begin in just four weeks.
Soil type is a pivotal part of the growing process, and thankfully, big bluestem is a versatile species. Plants will adapt regardless of soil conditions, whether you're working with thick clay, lush grass, or densely packed sand. They even grow tall and strong in poor quality, low pH soils.
Regardless of type, however, plant big bluestem in an area that's well-draining. Since those long roots need to spread out, proper drainage is a key indicator of success.
For best results, big bluestem should remain in full sunlight for at least eight hours a day. While partial shade is just fine for growth, full shade will inhibit your plants from reaching their full potential. The more sunlight, the merrier, so ensure you're planting in an open area where those rays will reach every portion of the grass.
While big bluestem is widely recognized as a drought-tolerant — even fire-tolerant — grass, water is still a vital part of its growth. While still growing, water your plants to a depth of one inch each week.
Once grasses have established themselves, however, watering requirements depend on the height you're aiming for. Adjust accordingly, watering heavily for taller plants and infrequently for shorter ones.
Fertilization isn't necessary to keep your big bluestem grasses growing strong; the plant's adaptability makes it a versatile option regardless of the elements. A nitrogen-rich fertilizer can help kickstart the germination process, however, encouraging quicker growth. This is optional, however, and no particular nutrients are needed for healthy growth.
Watch your big bluestem thrive during summer in USDA hardiness zones 4-9. With the exception of the far north and the hottest patches of the desert, this encompasses the majority of the U.S. Since grasses flourish during those scorching summer months, an ideal growing temperature rests somewhere between 80 and 90 degrees Fahrenheit.
Pruning such a large plant might seem intimidating at first, but all you need is a pair of gardening shears and a few free hours in the early spring. During this time, cut back old growth and remove dead foliage to ready plants for the warmer months. Growth usually kicks off in early April, with the majority happening in July.
Watch out for weeds, especially at the start of the growing season. Since many herbicides kill off grasses, they're a big no-no for big bluestem. Use mulch between plants to ward off weeds and keep a careful eye on your plants. Pull out any interlopers early when they're still small, and they won't pose any problems.
Big bluestem is easy to harvest from seed heads, so gather these once they dry out in September or early October; simply run your hand up the seed head and collect in a paper bag. Leave the seed heads inside these bags and set them in a warm area for one month to imitate the effect of moist, humid conditions, then store until winter's coldest, wettest conditions have passed.
Stored in a sealed jar, they can be safely kept for up to six months prior to planting in early spring.
Propagation through division is possible with big bluestem. Once the grass matures in early spring, start this process. Since the deep, lateral rhizomes can be hard to separate, a saw might be necessary to divide them properly. Make sure that any propagated grasses are kept moist until they've re-established themselves.
Unlike most prairie plants, big bluestem is virtually disease- and pest-free, making it much easier to care for and maintain. Red blotch is the disease known to affect these grasses most often, but it's a rarity.
Reduce the chances of disease even further by watering grasses at the base, ensuring that your plants receive sufficient sunlight, and keeping them spaced out sufficiently.
Big bluestem is an attractive foraging option, so many animal visitors will pop by. Damaging pests are rare, however, and grasses will quickly re-grow following any grazing.
Rust is the only visible pest that affects big bluestem, and all it does is discolor foliage. Regular watering, aeration, and minimizing shade can ward off any rusting effects.
Big bluestem's towering height makes it the perfect companion for black-eyed Susans, purple coneflowers, sunflowers, and other ornamental grasses, including switchgrass and prairie dropseed.
Planted in distinct spots throughout your property, such as around trees, fences, pathways, or the property line, it gives your natural landscape an elevated appearance. Wildlife and native flower gardens also look lovely with small additions of this lush grass.
As an ornamental grass, big bluestem makes a welcome neighbor to similar varieties, such as little bluestem, switchgrass, and prairie dropseed. Pawnee, however, is its most similar companion, although this species is more disease-resistant with hardier stalks and verdant leaves.
Planted alongside colorful prairie plants, including purple coneflowers and black-eyed Susan, big bluestem's sky-high grasses truly stand out.
While big bluestem makes a striking addition to home gardens, the USDA warns that the species can become invasive in some regions, potentially taking over existing vegetation. Since it requires consistent management to prevent overgrowth, the USDA also recommends consulting your local agricultural agency prior to planting.
Simultaneously, however, big bluestem can make an excellent addition to the local ecosystem, providing a sustainable source of food for everything from songbirds and butterflies to bison, deer, and prairie chickens. Landscape-wise, the species aids moisture retention in the soil and increases erosion control.
Other species from the Andropogon family include splitbeard bluestem, which contains two fluffy two-inch long seedheads without a leafy sheath. Virginia broomsedge has fuzzy flowers encased by leafy sheaths, and it turns a signature golden hue when the colder months kick in. Elliot's broomsedge is similar, with larger leaves and whiskerlike awns. These species only reach a maximum height of four feet, however, making them drastically shorter than their big bluestem cousins.
The Bison variety has enhanced cold tolerance to withstand northern climates; Kaw, Niagra, and Roundtree are used to improve existing planting sites. El Dorado and Earl are also similar, but they're used solely as forage grasses.