A clumping plant with a rapid growth rate, blue oat grass has been described as dramatic and yet well-behaved. It produces abundant shoots of blue-green grass stalks during the spring, but rarely self-seeds and doesn’t have the reputation of taking over in a garden. In summer, spikelets of tiny blue-green flowers bearing seeds appear at the top of the tall grass stalks in groups called panicles. These gradually turn to wispy brown plumage as fall approaches, imitating the appearance of oats. The plant is also very tolerant of environmental salt, pollution, and urban environments—making it adaptable for use in all types of landscaping. However, it does not prefer very hot or humid summer seasons, since it is a cool season grass. Plant a single blue oat grass plant for variety in your garden, or a whole row as a landscape border, a beautiful accent to your sidewalk or driveway, or as part of a xeriscaping plan.
Light
Blue oat grass thrives in full sun conditions. It can grow in areas with part sun and part shade, but it may become leggy under these conditions. Ideally, look for a location that receives at least six hours of direct sunlight per day for this plant.
Soil
Ensure that you plant blue oat grass in well-draining soil. Retained water leads to rotting of the roots or crown. For this reason, heavy clay-like soils are not ideal. Blue oat grass does best with an alkaline to neutral pH level in soil; a pH of 6.5 to 7.5 is considered best. These plants are also tolerant of environmental salt in the soil and are not adversely affected.
Water
Generally speaking, you won’t need to water blue oat grass often or much once established. This plant typically thrives just on the rainfall it receives. Keep in mind that the soil moisture should be average to dry at all times, so don’t overwater these plants or you could cause rotting of the root or crown. Blue oat grass is considered drought-tolerant, though it should be noted that periods of drought can induce a semi-dormant state in the plant.
Temperature and Humidity
Blue oat grass prefers a dry and cool climate. The distinctive blue hue that this plant is known for is most prominent in dry climates. In cool weather, these plants are semi-evergreen and retain their blue-green foliage through the majority of the winter—if conditions are not too harsh. In hot weather climates, summer temperatures may become too warm for the preference of blue oat grass, and the plant may not flower as expected.
Fertilizer
Hardy and healthy, blue oat grass doesn’t generally need supplemental fertilizer. When deciding whether or not your plant needs fertilizer, consider the health and color of the plant’s foliage. If you determine that the plant is faring poorly in the soil conditions, you could opt for an organic fertilizer that will be easily utilized by the plant—like compost, leaf mold, etc. If you decide to go with a conventional fertilizer, a 10-10-10 formula is typically recommended for ornamental grasses. Anything with too much nitrogen can cause the plant to overproduce foliage and underproduce flowers, leading to a leggy, poorly flowering specimen.
Types of Blue Oat Grass
Helictotrichon sempervirens ‘Saphirsprudel’: This variety is very similar in appearance to conventional blue oat grass. However, this cultivar has been developed to have a significantly more pronounced blue hue to its foliage, with slightly thicker grass shoots, and an increased tolerance for heat and humidity.
Pruning
Blue oat grass is famously low maintenance, but it’s beneficial to occasionally clear dead growth from each plant. You can easily pull out dead, brown stalks of grass by hand or use a garden rake to comb through the clump and remove old growth. When the plant goes into dormancy each winter, you can trim foliage down, leaving several inches above the crown of the plant. However, in some climates with mild winters, blue oat grass retains its characteristic blue-green color throughout the winter season. In such cases, it’s not necessary to cut back any growth and you can enjoy the foliage of the plant throughout the season.
Propagating Blue Oat Grass
The most popular way to propagate an ornamental grass like this one is by division; usually, this is done every three or four years in the spring before the growing season commences. To propagate blue oat grass, do the following:
How to Grow Blue Oat Grass From Seed
Blue oat grass can be propagated by seed, but many gardeners find this plant to have a low seed germination rate, so this method is not recommended. Instead, purchase plants and place them in desired locations around your landscape, then propagate per the instructions for division, above.
Potting and Repotting Blue Oat Grass
Blue oat grass can adapt to life in a container, but you’ll need to take steps to ensure that the soil has adequate drainage. In addition, some plants grown in containers lack the necessary nutrients for the sustained healthy growth of foliage in flowers. While blue oat grass plants in the ground rarely need fertilizer, you may need to supplement soil nutrients when this plant is located in a container.
Overwintering
This hardy perennial grass does not require special care during the winter.
Common Pests and Plant Diseases
Pests and disease are generally not a problem for blue oat grass, though they can develop rust fungus in overly humid conditions. This condition can be identified by speckled, rust-colored masses on the surfaces of leaves. Simply reducing the amount you water your grass will deter this moisture-loving fungus. Additionally, if you fail to space these plants far enough from each other (at least three feet is recommended), they may suffer from a lack of airflow and be subject to another fungal problem called tar spot. Thin your plants and keep watering to a minimum to discourage any fungal growth.
