Pruning Grassy Plants in Winter
Pruning grassy plants. Submitted
The wispy strands and bold spikes of ornamental grasses provide both softness and drama in the landscape, yet they’re also the target of a lot of bad hairdos and garden don’ts. Though misunderstandings about how to prune ornamental grasses abound, pruning grasses is pretty simple. Just figure out which category they fall under, whether evergreen or deciduous, large or small. This lets you select the best pruning method for each of your grasses, even if you’re not sure of the exact varieties you have.
Small and Evergreen
Sedge (Carex), blue oat grass (Helictotrichon), Mexican feather grass (Nassella tenuissima), lilyturf (Liriope), mondo grass (Ophiopogon)
These little charmers are some of the easiest plants to tuck into your garden, because they fit anywhere, have year-round good looks, and need so little care. If you’re unsure of whether these plants need a clean up, they probably don’t. The only reason to prune these grasses is to keep them looking sharp.
By the end of the growing season, brown foliage can pile up inside these plants and give them an unkempt appearance. One trick is to put on some rubbery gloves and run your fingers through the grass as though you were combing its hair. Any fully spent foliage will cling to the rubber and can be removed. This works especially well with blue oat grass.
For Mexican feather grass, all of the seedheads that develop in autumn can weigh down the plant, especially after the first rain. In this case, use a flexible metal rake to comb out the clumpy bits until it can move freely again in the breeze.
I try to avoid pruning sedges, lilyturf, and mondo grass, but if they become damaged and brown, it may be time to go in for the big chop. In late winter to early spring, use your hand pruners or hedging shears to reduce the height of your grasses by two-thirds. Because this type of pruning weakens your small grasses, it should be done no more than every two to three years.
After the “haircut.” Submitted
Small and Goes Dormant
Japanese forest grass (Hakonechloa), Japanese blood grass (Imperata cylindrica), switch grass (Panicum), fountain grass (Pennisetum)
If you like to prune, these grasses are satisfying to tackle. Because these varieties go dormant so quickly and obviously by turning brown at the start of cold weather, it’s easy to see they need pruning. When that time comes, cut these grasses back to a height of 3 inches. This should be done every year to give the new foliage a clean slate from which to shine.
Large and Evergreen
Flax (Phormium), Cordyline (Cordyline), silver spear (Astelia)
Unlike with deciduous grasses which are whacked to the ground, subtlety is key when pruning large evergreen grasses. There are many reasons to prune these plants, ranging from the removal of dead flowers and ratty leaves, to keeping plants right-sized for their space. In addition, the new growth on flax is more brilliantly-colored than the mature leaves, so periodic pruning keeps the foliage color bright.
The best way to prune all of these plants is to do so selectively. Just choose the oldest, tallest (when pruning for size) or most damaged leaves and cut them out at the base. This might seem like a time-consuming task, but once you get into a rhythm it goes quickly.
That said, sometimes selective pruning just doesn’t cut it, so to speak. If your plant is way overgrown, or must be cut to make room for painters, you can prune these plants severely in late winter to early spring. With flax, clumping types of Cordyline, and silver spear, use hedging shears to cut off all the foliage at the base. You’ll end up with a mound about 12 inches tall.
Trunk-forming types of Cordyline can be cut to bare sticks in late winter, and healthy plants will resprout vigorously right below the cuts.
While cutting off all of the foliage is not an ideal approach, these varieties grow back quickly. However, they have an awkward phase in their regrowth when the cut tips grow out, so about six weeks after the big chop, plan to remove any sprouting leaves that have obviously-cut, squared-off tips. This allows the fresh new growth to shine.
Always wear eye protection anytime you’re pruning spiky grasses. When you’re focusing on removing leaves at the base, it’s easy to lean down and get stabbed in the eye with a sharp leaf tip. That’s a definite pruning “don’t.”
Periodically pruning large, evergreen flax keeps the foliage color bright. Submitted
Large and Goes Dormant
Maiden grass (Miscanthus), Karl Foerster feather reed grass (Calamagrostis), Giant pheasant’s tail grass (Stipa gigantea)
There’s something about having a huge mass of foliage towering over your head that makes pruning these grasses seem like an intimidating task, but the concept is the same as with smaller ones. You can prune any time late fall through winter after the plant goes fully brown, as long as you time it before the grasses start growing again in spring. The grass itself will give you your cue. Maiden grass starts shedding soon after the new year, so as soon as you notice it making a mess, it’s time to prune.
Wear a long-sleeved shirt and gloves so the blades of grass don’t cut your skin (I’m lookin’ at you, maiden grass!). Use powered or handheld hedging shears (I like the Fiskars PowerGear hedgers for large/ thick-stemmed grasses) to cut the entire grass to about 8 inches tall.
Though small grasses are easy to clean up, big grasses make a big mess. Plan to put down a fresh layer of mulch after you’re done pruning. This covers any tiny bits of grass that won’t rake up, and gives your winter or spring garden a fresh look.
Genevieve Schmidt (Lic #986304) is a landscape designer and owns a fine landscape maintenance firm in McKinleyville, CA, specializing in the routine and skilled care of landscaped garden beds, such as pruning, weeding, raking, drip irrigation maintenance, as well as design and new plantings. See her work at www.GenevieveSchmidtDesign.com, and contact her via email or phone at gen@northcoastgardening.com or (707)822-2075 to discuss scheduling your winter pruning and garden cleanup.