Ornamental grasses have many uses in landscapes
The final plantings of ornamental grasses are under way by Pittsburgh Parks Conservancy horticulturalist Angela Yuele at the recently reopened Frick Environmental Center. As we walk to a bed filled with native flowers and grasses, a cool stream of water from an oscillating sprinkler splashes both of us.
It’s probably one of the last times these plants will get a drink unless it rains.
“When you’re planting this late in the season, watering is the key to getting any plant to establish,” Yuele says.
As the temperatures drop and with a little help from Mother Nature, the plants will catch on and be reliable perennials, returning each season.
The grasses offer many things for gardeners because they come in so many shapes, sizes and colors. They offer texture, verticality and more, she says. “I think they are nice in the garden for structure, and they are really easy to grow.”
One of the largest plantings includes drifts of beautiful, airy ‘Purple Love Grass.’
“We’re actually using them as groundcovers,” Yuele says.
The plant is a native that gets only around 18 inches tall, has a purplish seed tuft and makes a nice dense mat to suppress weeds. With the help of her team, she’s planted more than 2,000 of them.
“If you have large areas, masses look much better; they fit the scale of the landscape a little better.”
The different grasses she’s using here are clumping varieties as opposed to spreading types, but some can reproduce by seed — something gardeners should think about when adding the plant to their landscapes.
After turning off the sprinkler, Yuele looks over a bed of liatris — which just finished blooming — and cheery little yellowish orange coreopsis blooms. In between the flowers is another grass that sways in the breeze.
“Switch grass is one of my favorites,” she says.
It has a really airy seed tuft and gets only about 4 feet tall. Gardeners can get a lot of different cultivars, some with reddish tips and some with a bluish look. If home gardeners are looking for something a little more colorful, ‘Shenandoah’ switch grass is a quick grower that emerges green with red tips that darken through the season, eventually reaching burgundy in fall.
‘Sideoats Grama’ is another shorter grass growing in the bed. Tiny purplish, oatlike seeds form uniformly on one side of the stem. They are turning brown now as the season is ending.
All the grasses are planted in average native Pennsylvania soil — nothing special for these tough species.
Yuele tends other Pittsburgh Parks Conservancy gardens and has ‘Northern Sea Oats’ growing in a rain garden at the Schenley Park Cafe and Visitors Center, across from Phipps Conservatory in Oakland. The large clumping plant is a showstopper with its drooping oatlike seed heads, which on this day are fluttering in the wind, almost dancing as the breeze tosses them around. Early in the season, they are green but turn a sort of purplish bronze this time of the year, and the foliage will turn a coppery color after the first frost.
One other plant the horticulturalist uses all over the place, including at the Schenley Park bed, is a native called mountain mint.
“I love that plant because the deer don’t eat it,” she says. It even grows in Riverside Park, which is deer central. It gets about 2 feet tall and is a long bloomer, which makes it attractive to many pollinators and gardeners alike.
The Walled Garden in Mellon Park in Shadyside (behind Phipps Garden Center) is home to a type of Japanese grass called hakonechloa. It’s growing along the edge of a walk, softening the edges.
“It hasn’t been very aggressive,” Yuele says. “The chartreuse color has been great in a shady spot. We have that paired with brunerra that has a silver leaf. The combination looks really great together.”
Most ornamental grasses need to be cut back. There’s always debate on if this job should be done in the fall or spring. If left up, the birds and other animals will enjoy the seeds.
“My personal preference is what do I have time for,” Yuele says with a laugh. “Am I going to have time in the spring or the fall?”
She recommends wearing a dust mask to avoid sinus irritation when working with some grasses, such as porcupine or zebra that have little hairs on the stems.
In South Park, there’s a huge circular bed filled with amazing giants on East Park Drive. The wind is making them put on quite a show. Denise Schreiber, horticulturalist and greenhouse manager for Allegheny County Parks, prefers planting them in the spring as the bigger plants might not get properly established.
The biggest in this bed is Miscanthus floridulus and is at least 14 feet tall. Right next to it is a common, but beautiful, zebra grass (Miscanthus ‘Zebrinus’), 8 feet tall and filled with tassels, which is part of the beauty of the plants. Growing next to that one is a nice Miscanthus ‘Variegatus,’ which has white and green variegated foliage. As the sun gets lower, the blades of grass are backlit and shine.
After a few seasons, they need to be split. When the inside of the plant dies back and forms more of a ring, it’s time to separate the clump, which is done in the spring.
“You might need a backhoe,” Schreiber says with a laugh. She recommends saturating the soil before getting a sharp shovel to dig the plant out. “In some cases, you can actually use a pruning saw,” she says.
This South Park bed demonstrates how tall grasses can be a very effective screening plant.
One of her favorite varieties is grown as an annual, but it is a stunner.
“Pink muhly grass — it’s a beautiful plant,” she says. “I just love it to death, (but) it’s not hardy here. It’s very delicate, with an intense pink color.”
The plant gets about 3 feet tall and is most beautiful when it’s backlit.
Schreiber will use many grasses as a backdrop for smaller flowers. She says gardeners shouldn’t forget smaller varieties for containers to mix things up. The annual ‘Fireworks’ is a great choice, she says. The foliage is variegated with white, green, burgundy and pink running the length of the grass blade. In the summer, the plant gets purple tassels.
Schreiber, who is the author of “Eat Your Roses” (St. Lynn’s Press, $17.95), waits until spring to cut down her grasses, because she loves the winter interest the plants provide. They will fall down under the weight of heavy snow, but using garden twine to tie them up will work to keep them upright.
“Don’t put bows on them,” she says, laughing. “Don’t decorate them.”
Just a little snow makes the plants a star in the winter garden.
“If we get a light snow, it lays on them,” she says. “You get the really nice patterns on them, kind of like a fairy wand.”