Gardening Laidback Gardener Tip of the Day Ornamental grass Seasons

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

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

24 comments on “Do You Really Have to Cut Ornamental Grasses Back in Spring?

  1. Jeff Falk

    you mentioned shredding old maiden grass. what kind of shredder will do the job?

    • 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.

  2. What happens if you divide the grass after it’s begun growing? Like now in early june

    • Nothing much. Just water a bit more to compensate the damage caused to the roots by dividing them when they are in active growth.

  3. I am mostly interested in having our deciduous grasses grow taller. Does cutting them back impact their rate of growth or how tall they will get in a given season?

    • Fertilizer might help a bit, as will not letting them dry out completely, but cutting them back won’t stimulate taller growth. If you want tall grasses, you have to plant tall ones. Giant miscanthus (Miscanthus x giganteus, syn. M. floridulus) is one of the biggest ones and is hardy in most climates (zones 4 to 9).

  4. Heather Lane

    I have two zebra grass plants in my back yard that I have had for years. I cut them back in February early March which is a lot of work. They get about 7+ft tall. I usually have to tie a rope around them to keep the branches upright. Im planning on putting mesh fencing aroung them this spring so I won’t have to tie them. According to the article, you are saying I don’t need to cut them back. The old brown leaves will decompose and new ones will grow.
    If I comprehended that correctly, that would be fantastic.

    • Try it and you’ll see! Remember, they don’t get cut back in the wild either (well, at least the species does) and survive perfectly well.

  5. Annie Kanda

    It’s almost end of April. I cut back my grass in early spring but they have shown no sign of coming back. Is this normal?? The shorter grasses are about a foot tall with a lovely green color. However the tall ones are showing nothing!!
    Anne

  6. Thank you for this great advice! This is my first year with these grasses. I trimmed them down and I can see sprouts! Yay!
    How long do these take to reach their full heights?

  7. Kathie Johnson

    I cut my grasses back in March, I live near Ogden, Utah, but they show no signs of greening! Have I inadvertently killed them??

  8. sheri fayal

    I didn’t realize these grasses need cutting back. I’ve had my Forester Reeds for a year. They aren’t very tall but have more brown stalks than green. It’s May, should I go ahead and cut them back this late in spring? I live in Central Oregon climate

    • You don’t want to cut back this year’s leaves. Rather than remove dead ones one by one, want not leave them be this year… or cut off the the top part, above the new green leaves. Next year, you can cut them back earlier.

  9. MICHAEL SEWARD

    I’m sorry, but I just don’t see the need for the repetitive videos and advice from ” experts ” that continuously stress cutting Pampas grass back to the nubs all the time. This is a plant that left unchecked can grow to a height of 10 ‘ or better, with a large spread. The decision on how high you want it in your choice of space should be something you decided on when researching how this cool plant grows. It’s a fantastic cover for any space, particularly in a residential setting. I have 6 of these on my 1/4 suburban setting, and I simply take electric pruning shears and trim around the base to allow the leaves and other things that get caught up in it to be raked or blown out. the girth continues to expand, as does the height. There’s absolutely no need to shear the whole plant to 8″ above the ground annually. How do you expect it to grow 6 feet or higher if you whack it down every year? Let those things grow up and out and simply give it a trim, not a whack job annually. The entire plant will green up again. Contrary to the so called ” advice “, you will not get sliced to pieces picking up the leaves. A good pair of gloves, a rake, and a trash can are all you need. They have close to a 15 year life span, so experiment with height and girth, don’t just arbitrarily execute the entire plant every spring.

    • Yes, but part of the point of this article was to point out that you really don’t have to cut ornamental grasses back, that it’s optional. Nor was the text specifically about pampas grass, but rather more general.

  10. Good article. I was told by a friend who gave me the grasses to cut them down every year. The results have been good. I am at the age now that I would prefer not to do it. It’s mid May and the grasses look great. I like the green and brown mix.

  11. Rosemary

    I have 6 Miscanthus sinensis growing in a 3′ high stone and wood planter. They were great last year whenthey were two years old, but this year there are a couple that have only dead brown stalks on one side of them while the other side is growing, although slowly, and it is now late July. Can I dig up the half thatis dead without digging up the whole clump? Should I leave the rest of the plant as is and will it fill in? Thank you.

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