Agrostis

( ah - GROH - stis )

At-A-Glance Information

Agrostis, commonly called Bent-Grass, is a perennial grass genus that performs best where summers are on the cooler side. Plants will need full sun and regular to ample amounts of water to perform well. This grass makes a great lawn, but in hot weather it can succumb to fungal diseases. They are commonly employed for their turf qualities in golf courses (especially on putting greens) and sports fields. Use these grasses as groundcovers, lawns, or in Meadow landscapes.

Agrostis Species and Varietals

The genus Agrostis is a member of the plant family Poaceae, and includes between 150 and 220 species. Agrostis grows best in USDA hardiness zones 8 and above or Sunset growing zones 1-10 and 14-24. To find your zone, click here: Zone Map.

Agrostis blasdalei (Blasdale's Bent Grass)
Endemic to coastal Northern California, this species of bent grass prefers to grow in habitats like dunes and bluffs. Tufts of foliage reach up to a foot tall. Foliage is green, and flowers are borne in inflorescences of tiny spikelets.

Agrostis canina (Velvety Bentgrass, Brown Bent, Velvet Bent)
This species of grass forms a plant that reaches up to 30 inches tall when mature. It is in flower between the months of May and July. The species is native to most of Europe and temperate parts of Asia, extending from sea level to the alpine zone. This grass is sensitive to drought conditions, but is commonly seen in damp areas like ditches and lake margins. It is a popular lawn grass.

Agrostis capillaris (Common Bent, Colonial Bent, Browntop)
This species is native to Eurasia, and has been introduced to many areas of the globe. It typically grows in moist grasslands and open meadows, and is a pioneer of disturbed soils, roadsides, and agricultural land. Flowering panicles are finely-branched, forming a purple haze above grass from a distance. Plants reach up to around 45 inches tall when mature.

Agrostis castellana (Highland Bent, Dryland Bent, Dryland Browntop)
These cool-season grasses are native to Macaronesia and the Mediterranean region, and have been widely introduced elsewhere. It is considered an invasive species is some places. These plants are hyperaccumulators of zinc and lead in soils.

Agrostis densiflora (California Bentgrass)
These perennial grasses grow in tufts that reach between 4 and 34 inches tall when mature. They produce small inflorescences that are dense and cylindrical, reaching about a tenth of an inch in length. These plants are native to northern and central California, where they grow in immediate coastal habitats like dunes and bluffs.

Agrostis gigantea (Redtop, Red Top, Black Bent)
More coarse than other bent grasses, and not generally used for lawn grass. Can be used for overwintering other grasses as a 'topdressing'. These plants are native to Europe, and were historically used as pasture grasses. These grasses respond well to fires. Foliage is dull green.

Agrostis pallens (San Diego Bent Grass, Seashore Bent, Thingrass)
Fine-textured and native to the western United States. Great for planting in meadows; has a steady, fast, even growth with a good tolerance for shaded areas. This species makes a great eco-friendly lawn alternative. Mowing optional.

Agrostis scabra (Hair Grass, Rough Bent, Rough Bent Grass, Winter Bent Grass, Ticklegrass)
Native to Asia and North America, these plants are considered tumbleweeds. They are known in many areas as an introduced species, and can grow in a wide variety of habitats. These bunchgrasses grow upright to 40 inches tall and have rough leaves.

Agrostis stolonifera (Agrostis palustris, Agrostis alba) (Creeping Bentgrass, Creeping Bent, Florin, Spreading Bent, Carpet Bentgrass)
This is a high-maintenance lawn, which requires frequent mowing with a special mower. Varieties that are grown from seed include 'Emerald', 'Penncross', and 'Seaside'. Also sold as sod in strains 'Congressional' and 'Old Orchard'.

Agrostis tenuis (Colonial Bent)
Erect-growing grass, and a bit difficult to care for. This species of Agrostis has many varieties, including 'Astoria' and 'Highland', both of which are hardy and the latter of which is disease-resistant.

Caring for Agrostis

Agrostis can be planted via seed or sod, and should be situated in full sun to partial shade. Some species, for example Agrostis pallens, can take more shade and still perform well. Ensure that soil is well-draining, moderately fertile, and has a pH of between 5.5 and 7.5 (slightly acidic to slightly alkaline). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these grasses need regular water to stay healthy.

Fertilize a few times a year with a decomposed compost that is fine in texture and well-rotted. Apply a 1/4 inch layer over the area and gently work it in to the soil using a rake or brush. Water it in thoroughly after application, and then continue care as usual. Agrostis grasses can be left to grow naturally, or they can be mowed as a formal lawn. They are best when mowed to between 1 and 2 inches tall, but can also be used as turf mowed to 0.5 inches or less. Unmowed, they typically reach 2-3 feet tall and can be pruned to remove dead and damaged foliage to encourage new growth to emerge. Late winter or early springtime is the best time of the year to complete this type of pruning. Depending on the climate they are grown in, some Agrostis can stay green year-round, others may go dormant in cool weather.

Propagation

Agrostis, or Bent Grass, is best propagated by division or seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, especially if you are propagating a hybrid cultivar. To propagate your Bent Grass, follow the instructions below:

Propagating Agrostis by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, and a spray bottle. If you don't have any potting medium on hand, you can make some. A good potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded, and are typically held above the foliage on thin stems. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Get your container prepared. Water the seed tray or pot filled with soil, and ensure that good drainage is occurring. Place the seeds about a quarter inch under the soil surface. Cover them with soil and water with the spray bottle. Place the tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Alternatively and more commonly, Agrostis seeds can be direct-sown into bare areas of the garden, or dispersed over an existing lawn area that is becoming bare. When direct-sowing Agrostis seeds, make sure to prep the area by removing existing unwanted vegetation and debris, and prepare and level soil by adding some compost over the top. If seeding in a high-traffic area, it is recommended that barriers or caution tape be put up to avoid trampling small seedlings.

Propagating Agrostis by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil (any kind will do, though it does need to be well-draining), compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in early spring or fall. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Separate the removed patch of grass into sections using a sharp, clean knife or trowel. Ensure that each division has a healthy root system and a few shoots. Any dried out areas with dead roots can be tossed in the compost.
Prepare your pot(s) or new planting site(s) with well-draining soil and compost and rake it in. Water thoroughly, and then place divisions on top.
Keep soil consistently moist as the newly-planted divisions establish strong root systems in their new home. Provide regular waterings, especially during dry spells. It typically takes between 1 and 2 weeks for these grasses to develop their initial shallow root systems, and up to 30-45 days for their deeper roots to form.

Problems and Pests

Take care when planting these grasses in the landscape, as some of them (for example, Agrostis avenacea) are considered invasive weeds.
Agrostis plants can be susceptible to developing issues with the following pests and diseases in the landscape: