Do You Really Have to Cut Ornamental Grasses Back in Spring?

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By the time spring comes around, many grasses, like this Miscanthus, are looking worse for the wear and cutting them back is definitely an option. Source: www.fruitfulresearch.com

One garden task almost universally recommended for the end of winter or early spring is to prune ornamental grasses close to the ground. However, as a laidback gardener, I object to the generalization. Isn’t there any way of avoiding this task? Let’s look and see.

Evergreen Grasses

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Evergreen grasses, like this blue oat grass (Helictotrichon sempervirens), don’t need pruning. Source: francedesign.co

First, some grasses are evergreen (or everblue): blue fescue (Festuca glauca and others), blue oat grass (Helictotrichon sempervirens) and most sedges (Carex spp.), among others. Since they are evergreen, they don’t normally need pruning. Perfectionists can always pull out any dead or yellow leaves one by one (wear rubber gloves: the dead leaves will be easier to grip onto) in order to “clean” the plant, but otherwise they will look pretty good on their own with no special care at all.

Of course, sometimes after an unusually harsh winter, the foliage of even evergreen grasses can be severely damaged. If so, do cut them back to about 3 inches (7.5 cm) from the ground. This is for emergencies only, though. They don’t appreciate harsh pruning and this could weaken or even kill them if you repeat it annually.

Deciduous Grasses

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You can prune grasses back with pruning shears, but that’s a lot of work! Source: http://www.rhs.org

The majority of commonly grown ornamental grasses, however, are deciduous. Their foliage dies and turns brown in the fall, but often remains standing. Moreover, their winter effect, with arching leaves and feathery plumes still proudly erect, is one of their main attractions. But by the spring, the leaves are starting to collapse and the beautiful flower spikes have begun to crumble. It would seem that pruning is an absolute necessity!

But not so fast!

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Unpruned grasses go through a bit of an ugly duckling phase as the new leaves come in, but be patient! Eventually they’ll look just fine. Source: www.landscapeadvisor.com.

In nature, nobody prunes deciduous grasses. New leaves simply emerge through old, tired ones and eventually cover them up. And the old leaves eventually decompose and disappear, usually the same year. Remember too that the very best compost for any plant is its own dead foliage! Allowing the old foliage to remain intact will slightly slow down the speed at which the grasses seem to green up, but in no way harm them … and an unpruned plant will soon catch up to a pruned one.

If your ornamental grass is in the back of the garden, where the transition period—where you see a mixture of green and brown leaves (which can last up to mid-July)—is not so visible, you can simply walk away and let the plant take care of itself.

In spots where the grass is highly visible, however, you may want to cut the grass back in early spring. But there are still a few tips to help make the task less arduous.

Making Pruning Easier

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Pruning is easier if you bundle the stems and leaves together first. Source: northcoastgardening.com

First, before cutting the plant back, use a piece of cord to attach the stalks together, pulling them tight to form a sheaf. You may prefer to attach taller grasses in two or more places, giving a column effect. This way, you won’t have grass leaves in your line of vision as you prune and they’ll all be nicely attached in one single package, making for easier removal once you’ve cut them down.

All you have to do, then, is to cut the sheaf off about 4 to 6 inches (10 to 15 cm) from the ground. You can do this with pruning shears, of course, but then you’ll have to spend a lot of time bending or kneeling, a difficult position for older gardeners to maintain. Also, you’ll soon discover many grasses have sharp leaf edges, not something you want to stick your hand into.

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It’s easier and faster to cut grasses back with a hedge trimmer or chainsaw. Source: www.sebobo.us

Instead of pruning shears, try cutting your grasses back with a hedge trimmer or small chainsaw (the fastest method) or a string trimmer (slower but still effective). This takes little time and you can often do it without having to kneel.

Afterwards, run the sheaf through a shredder: chopped grass leaves make a great mulch!

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Freshly pruned miscanthus: new green leaves will soon hide the old clump. Source: www.plantsfordallas.com

Mother Nature’s Clean-Up Method

But there is an even lazier way to prune deciduous grasses: set them on fire!

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You can burn ornamental grasses to the ground and they’ll come right back up! Source: Lee Murphy, http://www.youtube.com

In nature, tallgrass prairies—the natural habitat of most of our ornamental grasses—usually burn every 1 to 5 years. Fire is therefore part of their natural lifecycle. Indeed, without fire, there would be no prairies or steppes: trees and shrubs would take over and the land would eventually become scrubland or forest. Fire cleans out dead stems and leaves, kills invading plants (notably tree and shrub seedlings) and fertilizes the soil. And grasses themselves are not adversely affected by fire: in fact, they have evolved to tolerate fire and even profit from this “natural pruning.” A grass that burns to its base will grow back much better than a grass that is cut back. Try it and see!

Of course, in this day and age, it is no longer possible to burn grasses in most urban areas. Check with your municipality to find out what the restrictions are.

If you do have the right to do so, any burning should be done in early spring, when the ground is still quite moist. Furthermore, for safety reasons, wait for a windless day and, before starting the burn, water all nearby non-grass plantings, soaking their leaves and stems. And stay nearby, hose in hand, to extinguish any stray spark.

To anyone who might complain that burning can’t possibly be environmentally friendly, think again. This is the most natural and environmentally friendly method of all, part of Mother Nature’s plan. How can you go wrong when you do what Mother Nature intends?20180429A www.fruitfulresearch.com

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2 thoughts on “Do You Really Have to Cut Ornamental Grasses Back in Spring?

    • A leaf shredder would do the job and is not too expensive. That’s what I use. An actual chipper-shredder would be faster, but they’re not cheap. You can’t really use a lawn mower as if you were shredding deaf fall leaves, though.

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