Sedges have edges, rushes are round, grasses have nodes from their tips to the ground
You’re probably familiar with the above rhyme and know that, while sedges have triangular stems, rushes’ are round, and those of grasses are hollow. This article describes only grasses, members of the important Poaceae family – fifth largest, with approximately 780 genera and 12,000 species.
Despite its size, it is still possible to recommend a few of those hundreds of species with specific objectives in mind. But first, be aware of the differences between cool and warm season grasses. While cool season grasses grow best in spring and fall with cooler temperatures, more rainfall, and less sunlight, warm season grasses prefer the warmer, longer days of summer. As a result, warm season grasses don’t begin to look good until mid-summer. When using them in the landscape, be sure to use other perennials that look good earlier in the growing season. For more information, check out Thomas Rainer’s article grounded design by Thomas Rainer: Warm Season vs. Cool Season Grasses .
Below, left, warm season Switchgrass (Panicum virgatum), and right, cool season Tufted Hair Grass (Deschampsia cespitosa) both photographed on May 27 in my full sun garden.
Benefits of using grasses in your landscape
1. Increasing biodiversity
Native grasses, having evolved alongside native wildlife, provide critical food, habitat, nesting sites, nesting material and shelter through all seasons. The following chart, from the University of Minnesota Extension, gives more detailed information.
Some of our native grasses are important larval host plants, providing food as well as shelter for caterpillars. Below, an example of a Dakota skipper shelter built at the base of Prairie Dropseed (Sporobolus heterolepis).
Warm season Little Bluestem (Schizachyrium scoparium), below left, a popular native grass in urban gardens, is a larval food plant for the Leonard’s Skipper, below right. It also feeds on Blue Grama (Bouteloua gracilis) and Switchgrass( Panicum virgatum).
2. Resilience/sustainability, especially of native grasses
Once established, they require no supplemental water or fertilizer. Most are extremely long-lived, and adapt well to weather anomalies. They are excellent choices for carbon sequestration, with greater biomass in their root systems below ground than their leaves above. Native grass meadow or prairie gardens are a superior ecological choice when replacing a traditional lawn.
Below, warm season Blue Grama (Bouteloua gracilis) and Sideoats Grama (Bouteloua curtipendula) – shorter grasses perfect for front yard rewilding.
3. Soil stability- dealing with erosion, poor water infiltration
Drought-resistant grasses, with their deep, extensive, root systems, are perfect plants to stabilize a slope.Their roots, coupled with dense above-ground vegetation, also absorb water, reducing the pooling or runoff during rain storms. When inter-planted with a compatible community of flowering native plants, their beauty often camouflages this critical role in the landscape.
Below, from www.rewildingmag.com , a slope ‘rewilded’ with a mix of native plants and Little Bluestem grass.
Good choices for slopes also include Big bluestem (Andropogon gerardii), Yellow Prairie Grass (Sorghastrum nutans), Switchgrass (Panicum virgatum) which can be used in dry or wet areas, Blue and Sideoats Grama grasses (Bouteloua gracilis and B. curtipendula), and for the shade, River Oats (Chasmanthium latifolium).
4. Screening/architectural interest
Grasses can also be used to quickly provide privacy and hide unsightly features, or to add structural interest in a landscape.
Below left, down at the bottom of my property, I used warm season non-native Giant Miscanthus (Miscanthus giganteus) to screen the street. This Miscanthus* is sterile and does not self-sow, and grows to a height of 3-4 m when in bloom. It is seen here behind a Giant Coneflower (Rudbeckia maxima) a planting at the top of the front yard. Below right, warm season Big Bluestem (Andropogon gerardii ‘Blackhawks’), a native cultivar reaching 1.8 m.
Below, the popular non-native cool season Feather Reed Grass (Calamogrostis X acutiflora) ‘Karl Foerster’ is often used for architectural interest.
5. Colour, texture, movement
Grasses can provide stunning ornamental effects in the landscape. They move beautifully in the breeze, contrast texturally with other herbaceous perennials, and bring changing colour as they age with the seasons.
Some striking examples: below left, warm season Little Bluestem, which changes from bluish to rose hues across the season, and right, warm season non-native Moor Grass (Molinia caerulea ‘Skyracer’), a tall grass that becomes golden yellow in late fall and, in my garden, is frequented daily by hungry finches.
For the shade, the two warm season grasses below offer beautiful texture and colour. Below left, Hakonechloa Grass (Hakonechloa macra ‘All Gold’), and River Oats (Chasmanthium latifolium), a prolific self-seeder, great for larger spaces.
6. Food
If interested in growing edible annual grains, check out the following article: Gardening with Grains – National Garden Bureau .
You may also want to get a copy of Brie Arthur’s Gardening with Grains, St. Lynn’s Press, 2019.
* A word about Miscanthus giganteus. Although some other Miscanthus species are invasive, this one is sterile and can’t spread by seed. Despite its possible contentious inclusion in this article, I have included it because its usefulness goes far beyond its ability to provide a quick screen or windbreak. It has strong, bamboo-like stems which protect insects, spiders, and small mammals over the winter. I harvest this material in the spring and use it as stakes or as a chop-and-drop mulch. The hollow stakes, open at the end, provide valuable nesting material for stem-nesting bees. They provide much-needed carbon-rich matter for my compost bins over the summer as well. It is drought tolerant, and will grow in nutrient-poor soils like the sand at the front of my property (dumped during the construction of my neighborhood). It is rhizomatous, but spreads slowly in this area. Like other grasses, it stores a tremendous amount of carbon below ground in its deep root system. Its life expectancy is between 20-30 years, and once it disappears from the landscape, its decaying roots will improve soil fertility and porosity.
Growing native grasses
For additional information on growing native grasses: