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Guide to gardening with ornamental grass

Guide to gardening with ornamental grass
Home & Garden

Guide to gardening with ornamental grass

Elegant but easy-care, ornamental grasses are being welcomed into more and more backyards. Gardeners love their graceful shapes and subtle colours. And their delicate flower tassels and plumes -- called inflorescences -- inspire evocative names, such as bottlebrush, cloud grass, foxtail and turkey foot.

Different grasses may grow from ankle-high to over-your-head -- in soft mounds, straight spikes, feathery fronds or arching cascades -- but most fall into one of two categories: clump-forming or spreading. Clump-forming grasses maintain their compact shape, so they're well-behaved in flowerbeds. Spreading varieties can be invasive (some imports even pose a threat to native species in the wild), so they should be chosen and controlled with care or simply confined to containers.

Perfect for eco-friendly gardeners, grasses are tolerant of many soil types and thrive with lots of sun, little rain and no chemicals or fertilizer. Native grasses, especially, are also an attractive food source for birds and butterflies.

Summer is the season when grasses really perform, providing motion, sound and a haze of colour. Left untrimmed until the spring, they will stand up beautifully all winter, showing off their silhouettes against the snow.


Growing tips

• For maximum impact, plant grasses in clumps of at least three plants.

Dig a roomy hole (two or three times the size of the root-ball) for each one. Turn the plant out of the pot, tease apart the roots and place it in the hole with the crown just above ground level so it won't get waterlogged. Fill in with soil and tamp down firmly. Water generously just until it gets established.

• When a clump gets too large or the centre begins to die back, wait until spring, then dig it up, leaving lots of soil around the edges. Using a pair of garden forks, pry apart the root-ball and immediately replant the divisions.

• In the spring, before new growth begins to sprout, cut back the plants. Trim grasses under one metre in height to about 5 centimetres tall; those over one metre to about 10 centimetres tall.


Designing with grasses

Piet Oudolf is an internationally acclaimed Dutch garden designer whose naturalistic planting style is shaking up traditional notions of border composition. Oudolf has brought his innovative ideas to many public gardens in North America, most recently to the Toronto Botanical Garden, where he has partnered with landscape architect Martin Wade on a design for the Entry Garden Walk and Arrival Courtyard.

Deceptively wild and spontaneous, naturalistic gardens succeed through careful selection and placement of plants. For Oudolf, grasses are essential elements that can create harmony, rhythm and excitement. Some tips on designing with grasses:

Grasses work best in combination with their natural companions: other hardy, long-lived, noninvasive perennials, most especially meadow flowers and prairie plants, such as bee balm (Monarda didyma), burnets (Sanguisorba), coneflowers (Echinacea) and masterworts (Astrantia).

Playing with form and texture is more important than devising artful colour combinations (grasses have a harmonizing effect on otherwise discordant hues). A typical naturalistic pairing might contrast the spiny, round flower heads of globe thistle (Echinops) with soft airy clouds of tufted hair grass (Deschampsia cespitosa).

Grasses can evoke different moods. Repeating one type of grass creates a calming rhythm; planted in uniform blocks, the same grass makes a powerful impression. Grasses planted in loose drifts are reminiscent of the countryside and impart an informal, nostalgic feeling.

• In fall, the burnished leaves of grasses blend with jewel-tone late-season perennials such as asters, sedums and joe-pye weed. In winter, grasses such as Calamagrostis, Deschampsia, and Miscanthus shine through the frosts.


12 grasses to try

On the shorter side:

1. Festuca glauca (blue fescue) -- Fine blades in dense tufts of up to 30 centimetres tall produce mauve inflorescences. Clump forming.

2. Hordeum jubatum (foxtail barley) -- Shimmering pinky-purple plumes reach about 45 centimetres tall. Clump forming.

3. Pennisetum alopercuroides 'Hameln' (fountain grass) -- Downy white flower spikes turn fawn in the fall and grow up to 60 centimetres tall. Clump forming.



4. Carex elata 'Aurea' -- Narrow, arching leaves, lemon-lime in colour, grow in thick tufts up to 60 centimetres tall. Clump forming.

5. Chasmanthium latifolium (spangle grass) -- This green grass grows up to 1.2 metres tall and matures to a bright copper, but it is also chosen for its distinctive oatlike flowers. Clump forming.

6. Panicum virgatum 'Huron Solstice' -- The light green leaves of this cultivar from Canadian hybridizer Martin Quinn are striped with red; pink inflorescences, reaching 1.2 metres tall, dance in a breeze. Clump forming.


Truly tall:

7. Andropogon gerardii (big bluestem, turkey foot) -- This grass grows up to 2 metres tall, with blue-green leaves and large purple inflorescences shaped like birds' feet. Clump forming.

8. Calamagrostis x acutiflora 'Karl Foerster' (feather reed grass) -- This reaches up to 75 centimetres tall, with pink inflorescences that almost double that height. Clump forming.

9. Panicum virgatum (switchgrass) -- The flat green leaves and delicate flower spikes grow up to 2.4 metres tall. Clump forming.



10. Hystrix patula (bottlebrush) -- Arching green stems grow up to 90 centimetres tall. Clump forming.

11. Sorghastrum nutans (Indian grass) -- The cultivar 'Sioux Blue' has blue-green blades that age to gold. Deep yellow flower tassels mature to bronze. This grass grows up to 90 centimetres tall. Clump forming.

12. Sporobolus heterolepis (Prairie dropseed) -- A mist of fragrant, pale pink flowers float about 60 centimetres in the air, above green leaves that turn gold. Clump forming.

Put this on your plan for spring planting -- and be sure to check out our Get out in the garden guide!


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Guide to gardening with ornamental grass