HOW, WHEN, AND WHY TO CUT BACK ORNAMENTAL GRASSES

Ornamental grasses are increasingly being used in our landscapes as an alternative to shrubs. In any region of the country, you can find native grasses that do quite well, and add textural variety and a soft, flowing aspect to the garden.

These plants are particularly attractive when planted in groups. Examples include any of the many miscanthus varieties, blue fescue (Festuca glauca), and switch grasses.

They are deciduous, rewarding gardeners year after year with fresh blades in solid or variegated green, red, and coppery colors, as well as prolific and attractive plumes and seedheads.

And while largely maintenance-free, many of these plants do benefit from an annual haircut. Let’s learn more about how to trim them up for maximum growth and beauty.

ENJOY THEM THROUGHOUT WINTER

While you likely won’t do any irreparable harm if you trim ornamentals back in the fall, we recommend you wait until late winter or early spring before you bring out the shears.

Many of these plants — especially those with spent plumes and attractive seed heads — offer alluring winter interest, particularly if snow or ice graces their foliage. Keeping the leaves around also protects the crown of the plant throughout the winter, but you do want to prune the old growth before the new growth begins. Leaving the dead material on too long can impair the crown’s warming and delay new growth by as long as three weeks.

“Elegant and flowy, ornamental grasses make a visually appealing addition to modern landscapes.”

If you delay the haircut until after new shoots have appeared, you’ll want to trim the old material carefully. If you cut the new blades, they’ll have a raggedy, unnatural appearance all season.

HOW LOW SHOULD YOU GO?

Start with a very sharp pair of hedge clippers. The 10-inch blades on these clippers will help you to get through any clump of grass quickly. Be sure to sharpen your blades frequently, as the grass will dull them.

Some gardeners use a hedge trimmer or even a chainsaw on older and tougher grass clumps.

Next, put on a long-sleeved shirt; the blades can be quite sharp!

Tightly tie twine, rope, or a bungee cord around the clump, about two feet up from ground level, and cut below the tie. This makes it easier to access the clump as you cut it, and it also provides you with a neat, tidy bundle to carry away and dispose of.

How short you cut these plants depends on whether they are cool-season or warm-season grasses. While the cool-season varieties grow best when temperatures are 60 to 70°F, the warm-season grasses like it hot, and prefer temperatures in the 80 to 95°F range. Warm-season grasses that are taller than 3 feet should be cut back to 4 to 6 inches from ground level. Shorter mature plants can be cut back to about 3 inches.

Prune cool-season grasses back by two-thirds.

LOW MAINTENANCE AND ATTRACTIVE

Elegant and flowy, ornamental grasses make a visually appealing addition to modern landscapes.

Cut them back as winter wanes and you’ll be rewarded with fresh and bright blades in springtime, and attractive plumes of seedheads in late summer and fall.