The most common questions we get about ornamental grasses care are when and how to plant, cut back and divide. Here are tips and techniques on how to maintain ornamental grass in your garden.
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Ornamental grasses have gained popularity recently. Ornamental grasses match most garden themes. Ornamental grasses provide height, movement, and long-season color. With the rise of ornamental grasses, care concerns have increased. Most often asked:
- When to plant ornamental grasses?
- Do I need to trim my grass back and if so when?
- How and when should I divide my ornamental grass?
When planting, trimming, and splitting ornamental grasses, follow these guidelines.
Cool-season, warm-season, and evergreen grasses exist. Grass kind slightly alters the rules.
- Cool-season grasses grow most in spring and autumn before temperatures reach 75 degrees Fahrenheit. They don’t grow in summer but keep their color.
- Warm-season grasses won’t sprout until mid-spring or early summer. Hot temperature boosts growth and blooming. Winter turns them brown.
- Evergreen grasses frequently resemble grasses but aren’t. Sedges and carex are grass-like but not grasses.
WHEN TO PLANT ORNAMENTAL GRASSES
The best time to plant new ornamental grasses in your landscape is spring or early fall. Planting before the summer’s heat (and often dry weather) arrives should give them enough time to root in before having to endure more stressful conditions. It can be tough to keep them watered well enough if planted in summer, so if you miss the spring window, aim to plant in early fall at least 6-8 weeks before the first frost.
WHEN TO CUT BACK ORNAMENTAL GRASSES
Cut back warm-season grasses in fall or by mid to late spring.
Colder weather browns warm-season grasses. Trim warm-season grasses whenever they turn brown. If you prefer autumn gardening or live in a fire-prone region, clip warm-season grasses to a few inches. For winter interest, keep dried grasses and seed heads in your garden if fire isn’t a worry. Snow-covered ornamental grasses are lovely. If you wait until spring to trim, cut them down to the ground (leave a few of inches) by late April before new growth starts. Trim back fall-looking ornamental grasses in winter.
Cut back cool-season grasses in very early spring.
Cool-season grasses look beautiful in cooler temperatures. Leave their foliage till spring and trim them back once the snow melts. Keep 1/3 of the plant. Over-trimming cool-season grasses may kill them.
HOW TO TRIM ORNAMENTAL GRASS
First, get thick leather gloves. Sharp ornamental grasses exist. Prune smaller grasses with pruning shears. Trim cool-season grasses to 2/3. Before pruning, several grasses may be tied together to make cleanup simpler. Short grasses may prevent this.
A chain saw, electric or gas-powered hedge trimmers, or a weed eater with a blade may be needed to cut a big, established clump of grass. Again, knot the tops and drop them into your compost pile. It’s difficult to prune one of these huge grasses using pruning shears. I know. I’m done!
WHEN TO DIVIDE ORNAMENTAL GRASSES
Dividing grasses increases plant numbers without cost. Occasional division helps grasses grow and rejuvenate. Dividing the clump rejuvenates grasses that perish in the core.
Divide warm season grasses anytime spring through mid-summer.
All ornamental grasses should be split while growing, not when blooming. Dormant plants won’t grow well after transplanting. Warm-season grasses grow in late spring or early summer and peak in summer heat. Warm-season grasses bloom in mid-to-late summer.
Divide cool-season grasses in spring or early fall.
Spring and autumn are cool-season grass growth seasons. Early spring is optimal for dividing these grasses. If you split them in the autumn, be cautious that winter’s freeze/thaw cycles don’t uproot them, as occurred to two of my coral bells last season.
Divide evergreen grasses and grass-like plants in spring only
Evergreen grasses never hibernate. Dividing plants hurts them. Evergreen grasses will struggle during winter after this damage.
HOW TO DIVIDE ORNAMENTAL GRASSES
Smaller grasses are divided like perennials:
- Dig up the grass and chop or rip it apart using your hands, pruning shears, a knife, or a sharp spade or trowel.
- Make sure that each piece has some healthy roots.
- Before the roots dry up, replant them. Cover exposed roots on sunny days.
Wear gloves because grass leaves are spiky. From experience, grass cuts hurt.
Larger grasses follow the same principles but are tougher to manage owing to their size and resilience. Some of these huge grasses might need three strong backs to remove. Dig or pry the clump out of the earth, ensuring sure each piece has roots.
An old hand or hack saw, an axe or hatchet (it may be easier to place the axe blade in one spot and then pound it through the grass clump using a large hammer or maul, I know I can never hit the same spot twice when swinging an axe), a sharp shovel, a reciprocating or concrete saw, or a chain saw (this will tear up your grass, so use it as a last resort) can be used to divide the plant into pieces. Big grasses are challenging.
Another way is to cut the grass to the ground and then wedge it with an axe. Excavate the fragments. After removing these bigger parts from the ground, use sharp pruning shears to break them up.
If your primary clump is healthy and hasn’t overrun its area, you may recreate it by cutting little pieces of grass from the periphery. This may be simpler than splitting the plant.
After removing the pieces from the main clump, cut dead material, replant, and water well. Newly split grasses require constant watering to establish. Once planted, you may reduce or stop watering.
DO ORNAMENTAL GRASSES NEED TO BE FED?
Ornamental grasses are often grassland or woodland plants. They get all their nutrition from their rotting leaves and the plants surrounding them. Fall leaf mulching over grasses mimics such circumstances. Grass doesn’t require fertilizer and frequently stretches and flops when fed.