Blue Grama (Bouteloua gracilis) is a perennial grass native to North America. Blue Grama grows in Canada, the United States, and northern Mexico. It is valued as forage for livestock and for its ability to tolerate drought conditions.
I. Appearance and CharacteristicsÂ
Bouteloua gracilis, the blue grama, is a long-lived, warm-season (C4) perennial grass, native to North America.
It is most commonly found from Alberta, Canada, east to Manitoba and south across the Rocky Mountains, Great Plains, and U.S. Midwest states, onto the northern Mexican Plateau in Mexico.
Blue grama accounts for most of the net primary productivity in the shortgrass prairie of the central and southern Great Plains. It is a green or grayish, low-growing, drought-tolerant grass with limited maintenance.
Blue grama has green to grayish leaves less than 3 mm (0.1 in) wide and 1 to 10 in (25 to 250 mm) long. The overall height of the plant is 6 to 12 in (15 to 30 cm) at maturity.
The flowering stems (culms) are 7 to 18 in (18 to 46 cm) long. At the top are one to four, usually two, comb-like spikes, which extend out at a sharp angle from the flowering stem. Each spike has 20 to 90 spikelets. Each spikelet is 5 to 6 mm (0.20 to 0.24 in) long, and has one fertile floret and one or two reduced sterile ones. Below the florets are two glumes, one 1.5 to 3 mm (0.06 to 0.12 in) long and the other 3.5 to 6 mm (0.14 to 0.24 in) long. The fertile floret has a lemma (bract) 5 to 5.5 mm (0.20 to 0.22 in) long, with three short awns (bristles) at the tip, and the sterile floret has a lemma about 2 mm (0.08 in) long with three awns about 5 mm (0.2 in) long. If pollinated, the fertile floret produces an oblong-elliptic brown seed 2.5 to 3 mm (0.10 to 0.12 in) long. When the seed is mature, the whole spikelet detaches, except for the two glumes, which remain.
The roots generally grow 12 to 18 in (30 to 46 cm) outwards, and 3 to 6.5 ft (0.9 to 2.0 m) deep.
Blue grama is readily established from seed, but depends more on vegetative reproduction via tillers. Seed production is slow, and depends on soil moisture and temperature. Seeds dispersed by wind only reach a few meters (6 ft); farther distances are reached with insects, birds, and mammals as dispersal agents. Seedling establishment, survival, and growth are greatest when isolated from neighboring adult plants, which effectively exploit water in the seedling’s root zone. Successful establishment requires a modest amount of soil moisture during the extension and development of adventitious roots.
Established plants are grazing-, cold-, and drought-tolerant, though prolonged drought leads to a reduction in root number and extent. They employ an opportunistic water-use strategy, rapidly using water when available, and becoming dormant during less-favorable conditions. In terms of successional status, blue grama is a late seral to climax species. Recovery following disturbance is slow and depends on the type and extent of the disturbance.
II. How to Grow and Care
Sun and Temperature
Blue grama plants grow best in full sun, with at least 6 to 8 hours of sunlight per day. They do best in USDA growing zones 5-9. Blue grama’s perennial origin means that it will go dormant in the wintertime and come back with new growth in the spring. When planting from seed, it’s best to wait until the fall so the seed can cold stratify over the cold seasons. This heat-loving native grass requires warm temperatures of spring in order to aid germination.
The most active period of the growing season occurs when temperatures are between 70-90 degrees Fahrenheit. In addition to being heat tolerant, it’s also cold tolerant. Growth will slow as the nighttime temperatures begin to drop in the fall, and eventually, in the winter, it will turn tawny, but it will never completely die back. Although blue grama grass is native to western Colorado, it does have an elevation limit on the hardiness of 7500 feet.
Water and Humidity
Since blue grama grass loves the full sun and warm temperatures, do your watering in the morning before the heat of the day. This way, the water will be able to penetrate to the roots before the sun has a chance to evaporate the moisture. As your native grasses become established, their watering needs will change.
In their first year of growth, they should be watered at least 2 times per week during the growing season. In their second year, this can be reduced to 1 time per week. In their third year, this can be further reduced to 1 time every 1-2 weeks. In the wintertime, snowfall should provide sufficient moisture, but in particularly dry winters, they can be watered once a month as long as air and soil temperatures are above 40 degrees and the soil is not frozen.
Once your blue grama grass has reached maturity, then they become extremely drought resistant and can survive on as little as 7 inches of annual rain. During extended dry spells – even in the heat of summer –if they aren’t irrigated, they go dormant and may turn brown but will spring back to life at the first sign of moisture. If you wish to keep your grama grass green, then you may choose to water it during these periods.Â
Soil
This bunch grass is known for tolerating a wide range of soil types. Blue grama grows naturally in dry prairies and is often found in rocky or clay soil. It does best, however, with well-draining soil. It is not found in wet, poorly drained soils and can be damaged by overwatering or soggy/waterlogged soil conditions. For this reason, it does not tolerate being planted in areas with a high water table.
Blue grama grass also prefers neutral soil and can’t handle acidic conditions. If you’re planting in a highly rich medium, add sufficient amounts of sand to help with drainage. Fine sandy soils are just fine for this grass.
Fertilizing
One of the benefits of growing blue grama grass is that it’s very low maintenance. It can survive on very little water, can tolerate a wide variety of soil types, and doesn’t require any regular fertilizer or soil amendments. Although fertilizing isn’t necessary, it can be especially helpful if you’re using it as a native alternative and want to maintain its green color. Fertilize with nitrogen once a year in June. When starting blue grama grass from seed, it can benefit from the boost of a layer of compost at the planting site, although this isn’t a must.
Pruning
To understand the pruning requirements for blue grama grass, you must first understand its natural growth habits. During the active growing season from mid-May to October, the blades will be light green in color. During late summer, the seed heads will form (when grown as an ornamental and left unmowed). During the winter, it will go dormant and turn light brown in color. It can be left standing to add interest to your winter landscape. Then in February, it can handle mowing to a height of 3 inches and will then put on new growth in the spring.
When used as a lawn alternative, it can handle being regularly mowed to a height of 3 inches, or it can be left to grow a bit taller for a more natural lawn appearance. This native grass can tolerate heavy foot traffic, so it would be fine in an area that children and pets frequent. As winter approaches, let your grass gain some height to direct energy toward the root system. It will brown during the winter but will come back to life in the spring.
Propagation
Like most grasses, the blue grama grass species is mainly propagated by seeds. This is especially true when using this plant as a lawn alternative which will require you to broadcast seeds across a large area. There are native seed companies that sell seeds of wildflowers and native grasses mixed together. To plant them, broadcast the seeds over an area in the fall and then cover them lightly with a fine layer of sandy or silty material to keep them from blowing away in the wind. Then water them in and water once every two weeks to help them germinate.
This is much easier than transplanting bunches as they are slow growing and take their time spreading. Growing from transplants is the ideal method of propagation when using Bouteloua gracilis as an ornamental grass. Then you get the benefit of a fully established plant in your landscape much sooner. You can also plant plugs of grass mixed with species of native wildflowers.
Pests and Diseases
- Growing Problems
Most growing problems occur when this plant is overwatered. If the ground feels spongy, you notice standing water, or if your grass is suddenly wilting, this could be a sign you’re overwatering. This plant is highly drought tolerant, and it’s better to water less rather than overwater. It can bounce back and thrive on very little moisture. However, too much moisture can cause damage.
- Common Pests
Grasshopper species have been known to chomp on the leaf of blue grama grasses, but in general, their feeding isn’t enough to cause major damage to the plant. Usually, the grasshopper population is easily controlled by your neighborhood birds and other small wildlife.
- Common Diseases
The most prevalent disease issue with this grass is fungal rust which, as its name would suggest, is caused by a fungus. One sign of rust fungus is small reddish-orange spots on the leaves. This fungus prefers warm, wet, and humid environments. Watering only in extreme drought and only when the clumps of grass have a chance to dry in the coolest part of the day can help avoid these issues.
Neem oil or a copper fungicide can help control rust applied to the foliage can help control rust on the grass. Careful applying these in native habitat restoration projects and pollinator gardens, as they can be dangerous to pollinators. Â
III. Uses and BenefitsÂ
Welcomed in any garden style, it is versatile and can be used as a specimen plant, in groups, or en masse. It is ideal in borders, providing texture, color, and contrast. A great choice for rock gardens, prairies, and naturalized areas. It can be used as a ground cover in dry spots. Flowers are excellent in dried arrangements.
