5 Hot Cool-Season Grasses
Chill out this spring with resilient grasses that will kick-start your garden and may just last all year
Grasses have been all the rage for a few years running, and I for one hope they never go out of style. What you may not know is that grasses fall into two categories: cool season and warm season. It's important to understand the differences between the two.
As their name suggests, cool-season grasses grow when the weather is cool. They're straight out of the gate in spring, even when you might be thinking it's a bit chilly. In mild climates, many are evergreen and grow right through winter. Cool-season grasses may go dormant and even brown in high summer, but with careful siting (a bit of shade in the heat of the day) or careful planning that takes advantage of that dormancy, they're great garden characters through a huge chunk of the year.
As their name suggests, cool-season grasses grow when the weather is cool. They're straight out of the gate in spring, even when you might be thinking it's a bit chilly. In mild climates, many are evergreen and grow right through winter. Cool-season grasses may go dormant and even brown in high summer, but with careful siting (a bit of shade in the heat of the day) or careful planning that takes advantage of that dormancy, they're great garden characters through a huge chunk of the year.
The grass I'm telling people about most these days is tufted hair grass (Deschampsia cespitosa, zones 4 to 9). Think of it as a cross between 'Karl Foerster' and blue fescue — a tidy, globe-shaped green clump that explodes in summer with flowers of the cleanest, freshest apple green. Those fade to wheat and hover above clumps like raindrops suspended on rods. (See an example in the background in the next photo.) Hair grass is native to northern and western North America. It grows well in sun or partial shade, and damp or dry soil; it likes a bit of shade in the heat of the day. Cultivar 'Northern Lights' has variegated foliage that turns pink when the weather cools.
Photo by Rasbak via Wikimedia Commons
Photo by Rasbak via Wikimedia Commons
Blue oat grass (Helictotrichon sempervirens, zones 4 to 8) makes for a perfect steely blue sphere, like blue fescue but bigger. This grass may be a cool-season grower, but it does best with soil on the dry side and plenty of sun. Similarly hued flowers appear in early summer and fade to the namesake oat color by fall.
Photo by Daderot via Wikimedia Commons
Photo by Daderot via Wikimedia Commons
Another underused cool-season grass is autumn moor grass (Sesleria autumnalis, zones 5 to 8). Like tufted hair grass, its apple-green-flowered comrade, this one is a must for fans of chartreuse. Its spiky clumps bloom with little thumbs of soft flowers that shimmer and fade to white with a hint of green. This grass isn't a huge fan of humidity, but it's a fine addition to dry sites in sun.
Photo by Lilly M via Wikimedia Commons
Photo by Lilly M via Wikimedia Commons
Rounding out our group is a classic favorite grass for shade. It's March in the Northeast right now, but I noticed that my river oats (Chasmanthium latifolium, zones 3 to 8) are already growing. Cool season indeed! This grass is famous for its oatlike flowers, pictured here, that dry and make for fantastic fall accents. It does seed around, so be wary if you're particular about that, but I can attest that it's far less promiscuous in dry shade than damp. River oats are native to wetlands from the Mid-Atlantic and Midwest throughout the Southeast and west of Texas, so if you live in those regions and get stray seedlings, you can at least be assured you're making a positive contribution to your native ecosystem.
Photo by Eric in SF via Wikimedia Commons
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Photo by Eric in SF via Wikimedia Commons
More:
Ornamental Grasses in the Landscape
Add Texture With Grass
Mass Plantings Make an Elegant Garden Impact
Photo by Daryl Mitchell via Wikimedia Commons