by Raakel Toppila
The ornamental value of grasses has only recently been recognized. Their graceful habit, animated movement, and fine textured foliage have proven them a worthy addition to our gardens. However, the ornamental value of our own native grasses has yet to be discovered.
Warm or cool season grasses
Grasses are often described as either warm or cool season. These characteristics do not refer to the hardiness of the plant but to their season(s) of growth.
Cool season grasses begin to grow in late winter or early spring. The optimum temperature for growth is between 15 and 23 degrees Celsius. They flower in late spring and summer. Growth slows or the plant enters a period of dormancy in the hot summer months. When temperatures cool in the fall they begin to grow again. Some even continue to grow throughout the winter months.
Warm season grasses thrive in the heat of summer. They grow best at temperatures between 26 and 32 degrees Celsius. They produce flowers during the summer months and go dormant in the fall. Dormant foliage and seed heads of warm season grasses persist. providing winter interest and food for birds.
Growth habit
A second way to classify grasses is by their habit. Some are described as clump forming, bunching, or tussock grasses. These types of grasses spread by tillers and create a compact, clump-like growth. In a garden setting these grasses are often preferred because the plants remain contained within their planting area.
Running grasses spread by rhizomes (under ground) or stolons (above ground). Running grasses may become invasive through their ability to form dense mats quickly. Running-type grasses are often used as lawns.
Be aware of the likelihood of a grass to self-seed. Chasmanthium latifolium, Northern Sea Oats, for example, is a clump-forming North American native grass that produces a multitude of seeds, many of which germinate the following year. This grass can spread quickly in the garden and may become a problem. Despite this drawback, Northern Sea Oats is known for its unique seed heads. One way to control its spread is to cut the grass to 10 centimetres in height soon after the seeds appear.
Maintenance
Once established, ornamental grasses require very little maintenance. The frequency of watering can be adjusted to the individual needs of the grass species. Most grasses have few, if any, pest or disease problems. Perhaps the most important maintenance technique is cutting back the grass to a height of 10 centimetres. This can be done with hedge shears in February or March before new growth appears from the crown of the plant.
Dividing is another maintenance technique that is required for clump-forming grasses. As the plant ages it may flop or die in the centre. Division will help rejuvenate the grass and keep it looking its best. Divide warm season grasses in late winter or early spring. Cool season grasses can be divided in the fall, winter, or early spring. Cut the foliage back to a height of 10 centimetres. Remove the clump from the ground, leaving soil around the root ball. Use a saw, spade, or shovel and divide into smaller clumps. Keep in mind, the smaller the clump, the longer it will take to reach full size. Share the divisions with friends or transplant back into the garden.
Some native ornamental grasses to try
Andropogon
gerardii
Big Blue Stem,
Turkey Foot
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm season, perennial grass.
1.2–2.0 metres tall
Blue-green to silvery blue foliage with purplish flower spikes.
Dry soils, open prairies, and shores from Saskatchewan
to Quebec.
Full sun, well-drained soil, tolerant of considerable drought.
Screens, erosion control, specimen, masses, winter interest,
arrangements.
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Bouteloua curtipendula Side Oats
Gramma
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm season, perennial grass.
0.3–0.6 metres tall.
Grey-green, fine-textured foliage produces a one-sided arrangement
of purplish flower spikes in early summer.
Dry prairies and sand hills from southern Ontario
to Saskatchewan.
Drought tolerant and adaptable to a wide range of conditions. Grows best in well-drained fertile soil in
full sun.
Use in masses, for erosion control, or in arrangements.
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Carex muskingumensis Palm Sedge
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Description
Native habitat
Preferred site
Landscape uses
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Slow-spreading, cool season, perennial grass.
0.6–1.0 metres tall.
Foliage resembles palm fronds, giving it a tropical appearance.
Moist or swampy ground from Manitoba
to Ontario.
Moist conditions are required.
Tolerates either sun or shade.
Use in masses along streams, at the edge of a pond, in water
gardens, pots, or tubs.
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Deschampsia caespitosa Turted
Hairgrass
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, cool season, perennial grass.
0.3–1.0 metres tall.
Forms dense clumps of dark green foliage. Flowers are showy, loose
panicles.
Damp soils, shorelines, and meadows from Alaska
to Newfoundland to southern United States.
Moist, rich soil in light shade.
Use in masses or as specimens, along streams or on slopes.
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Deschampsia flexuosa Crinkled
Hairgrass
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, cool season, perennial grass.
0.3–0.6 metres tall.
Tufted grass with shiny foliage and loose, delicate flowers.
Dry, open soil from Newfoundland
to British Columbia.
Grows best in light shade and moist conditions. Tolerant of dry
soils.
Planted as a specimen or in masses.
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Elymus canadensis Canadian Wild Rye
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, cool season, short-lived perennial grass.
0.6–1.5 metres tall
Blue-green foliage. Green panicles droop to one side.
Dry, sandy or gravelly soil from British
Columbia to New
Brunswick.
Adaptable to a wide range of soils and conditions. Grows best in
moist, fertile soil in full sun.
Naturalizing, groundcover, attracting wildlife, arrangements,
erosion control.
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Panicum virgatum Switchgrass
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm season, perennial grass.
1.2–2.0 metres tall.
Green-to-grey green foliage turns yellow in the fall. Pinkish
flowers emerge, changing to brown in the winter.
Dry or moist sandy soils from Saskatchewan
to Quebec.
Tolerates a wide range of soils.
Prefers moist, fertile soil and full sun.
Use as a specimen or in masses, screens, attracting wildlife.
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Schizachyrium scoparium
Little Bluestem
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm season, perennial grass.
0.6–1.5 metres tall.
Light-green foliage changes to bronze or orange in the fall.
Prairies from Saskatchewan to Manitoba.
Thrives in full sun and tolerates almost all soil conditions. Does
not do well in wet soils.
Use in masses or as specimens, attracting wildlife.
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Sorghastrum nutans Indian Grass, Gold Beard Grass
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm season, perennial grass.
0.6–1.0 metres tall.
Upright habit with foliage ranging in colour from light green to
almost blue. Flowers form on stiff upright stems 0.6–0.9 metres above the
foliage.
Prairies, dry slopes, and open woods from Saskatchewan
to Quebec.
Tolerates a wide range of soils. It grows best in rich, moist loam
soils in a sunny location. It is drought tolerant once established.
Use in masses, as a screen, or for naturalizing.
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Sporobolus
heterolepis
Prairie Dropseed, Northern Dropseed
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Description
Native habitat
Preferred site
Landscape uses
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Clump-forming, warm/cool season, perennial grass 0.6–1.0 metres
tall.
Fine arching foliage turns from an emerald green to a golden brown
in the fall.
Rocky ground and prairies from Saskatchewan
to Quebec.
Prefers dry, rocky soil in full sun. Tolerates a wide range of climatic
conditions and soil types.
Use in masses as a groundcover or for erosion control, xeriscape
gardening, and attracting wildlife.
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