How to prune clumping bamboo

April 24, 2017

I’ve known many people who are afraid to plant any kind of bamboo, even a clumping type, for fear it will take over their yard — and with good reason. Here in Austin, many a back yard is clogged with running bamboo, which is often planted for privacy along a fence but quickly metastasizes, spreading across the lawn and into the neighbors’ yards as well.

Clumping bamboos, however, don’t “run,” making them garden-safe.* Even so, they grow vigorously enough to require regular pruning in order to look their best. Take ‘Alphonse Karr’ bamboo, for example (pictured here). I usually prune it twice a year, in late spring and early fall, to keep it from looking like a shaggy green beast and to give it shapely definition. Here it is in beast mode (above) — lots of leaves amid a thicket of culms (the canes) that are arching over the gutters and blocking a window.

And here it is after an admittedly exuberant pruning. I removed about a quarter of the culms entirely, all the way to the ground (never cut them off halfway, which causes ugly side growth), and limbed up others, revealing the green-and-yellow stripes on the exposed canes.

I start by trimming off the side branches that grow along the culms, starting at ground level and pruning up to just above my head. How high up you prune should depend on the height of the bamboo. You do still want to have plenty of leaves up top to keep the plant healthy.

Using a pair of sharp bypass pruners, clip off the stems close to the culm, holding onto them with your free hand to keep from making a mess below. Just toss them in a bin for composting later. And be careful not to nick your free hand with the pruners!

I use a long-handled pruner for getting into the culms and pruning out weak ones or those leaning over the gutter. I also thin out culms that spread beyond the original planting.

And that’s it. It’s a pretty Zen activity, really. Here’s another look at the overgrown beast, before pruning. Nothing wrong with this, of course, if you need a green screen that won’t run, but it’s too much for a small space like this one.

And here it is after an hour of pruning. Leggy, airy, and out of the gutter!

Here are a few more bamboo-pruning resources:

I first learned about limbing up bamboo on the Austin blog Growing Optimism, which also features a nifty bamboo-and-zip-tie fence to hold leaning canes away from paths: Growing bamboo in a narrow space – pros, cons, and a solution for support

For expert advice, watch Cass Turnbull of Plant Amnesty explain how to prune bamboo: How to Prune Bamboo – Instructional Video w/ Plant Amnesty

Also, watch Austin’s own Merrideth Jiles share his extensive knowledge of bamboo, including pruning tips, on Central Texas Gardener: Bamboo Basics | Merredith Jiles |Central Texas Gardener

And finally, here’s a helpful list of clumping bamboos for Austin from The Great Outdoors nursery. By the way, although TGO’s guide says bamboo needs to be watered twice a week during Austin’s summers, I have not found this to be true in my garden. Once a week works fine for my established bamboos ‘Alphonse Karr’, ‘Tiny Fern’, and, to a lesser extent, Mexican weeping bamboo.

*Note: Clumpers do gradually expand but not aggressively. Please, do your research to learn which is which before buying. I can’t think of any reason to plant a runner, frankly.

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