Which bamboo needs a barrier?
Find the row that matches your bamboo. If two rows fit, follow the one that calls for a barrier.
| Your bamboo | Barrier? | What to do |
|---|---|---|
| Running bamboo | Yes | Bamboo Shield, by USDA zone. Zones 4–7: 24 in for bamboo up to about 25 ft, 30 in for anything larger, timber bamboo included. Zone 8: 30 in. Zones 9–11: 36 in. One depth deeper in loose or sandy soil; at 36 in, stay at 36 in. |
| Not sure which kind | Yes | Plan for running bamboo. If you can't name it, use the larger-bamboo row: 30 in in zones 4–8, 36 in in zones 9–11. |
| Yushania, a clumper that spreads like a slow runner | Yes | Treat it as running bamboo |
| Clumping bamboo near a pool, foundation or property line | Optional | 36 in, if you want a firm edge. Set it outside the clump's mature width. |
| Clumping bamboo with room to widen | No | Skip the barrier. Cut shoots you don't want at ground level. |
What's the difference between running and clumping bamboo?
The difference is under the soil, in the rhizomes. Rhizomes are stems that grow underground. They spread the plant, and they are what a barrier is for.
Running bamboo has long rhizomes that grow sideways. Most stay in the top 12 to 18 in of soil.
A new cane can come up at any node, one of the rings along a rhizome, feet away from the grove. The Royal Horticultural Society says running types can spread more than 3 ft a year.
Clumping bamboo has short, thick rhizomes. Each one curves up and becomes a new cane right beside the cane it came from. The University of Florida extension service says clumpers grow only a few inches wider each year.
How can I tell which kind I have?
Check the botanical name first, then the plant. One running sign is enough: plan for running bamboo.
Check the botanical name
Look on the plant tag, the receipt or the seller's listing. The first word of the botanical name is the genus, and it settles the question.
| Genus (first word of the name) | Type |
|---|---|
| Phyllostachys (includes Phyllostachys aurea, the plant most often sold as golden bamboo) | Running |
| Pleioblastus (often short, used as ground cover) | Running |
| Sasa | Running |
| Pseudosasa (includes arrow bamboo, Pseudosasa japonica) | Running |
| Yushania | Clumping, but spreads like a slow runner. Treat it as running. |
| Fargesia (often sold as fountain bamboo) | Clumping |
| Bambusa (grown in warm areas such as Florida) | Clumping |
| Borinda, Thamnocalamus | Clumping |
A tag that says "bamboo" or "clumping" with no botanical name isn't proof. Neither is a common name. "Golden bamboo" and "giant timber bamboo" each name both runners and clumpers.
Check the plant
| What to check | Running bamboo | Clumping bamboo |
|---|---|---|
| Where new shoots come up | In the lawn or a bed, feet from the nearest cane | Only at the edge of the clump, close to other canes |
| How the canes are spaced | Spread out with gaps between them, like a small forest | Packed tight in one dense clump |
| The cane, just above a branch | Mainly Phyllostachys: a flat groove runs the length of the section and switches sides at each node. Two branches per node, one bigger. | No groove. Many runners have none either. |
| The rhizome, at the edge of the planting | Long, running sideways, with roots at its nodes | Short, thick and curved, turning up into a cane |
To see the rhizomes, dig a small hole about 18 in deep at the outer edge of the planting. That covers the 12 to 18 in layer where most running-bamboo rhizomes grow. Call 811 before you dig.
In cold areas, Fargesia is the main clumper. Most other bamboo grown there runs.
What if I'm still not sure?
Plan for running bamboo. If you can't name it or its mature height, use the larger-bamboo row for your zone: 30 in in zones 4–8, 36 in in zones 9–11. Bamboo barrier depth and thickness has the full climate chart, and Bamboo Shield lists prices and lengths.
- Young runners look like clumps. A new running planting often grows slowly for a year or two, then sends up shoots many feet out.
- The two mistakes don't cost the same. A barrier around a clumper costs you the barrier. A runner with no barrier can reach the yard next door. University of Maryland Extension says running rhizomes can spread a hundred feet or more where nothing stops them.
Does a clumping bamboo ever need a barrier?
Most don't. A clumper with room to widen needs no barrier. Keep it in bounds by cutting unwanted shoots at ground level; they won't grow back.
Near a pool, foundation or property line, a firm edge is optional. If you want one, use the 36 in depth. It is the only Bamboo Shield made at 100 mil, and a widening clump presses hard on a barrier.
Install it the same way as for a runner: 2 in above the finished soil, smooth face toward the bamboo, top tilted slightly outward. For the 36 in barrier, that means a 34 in trench. Call 811 before you dig. The Bamboo Shield install manual covers each step.
How much room should I leave around a clump?
Set the barrier outside the clump's mature width, on every side, with room inside the line to cut edge shoots and thin old canes. Find the mature width on the tag or ask the grower.
Near a property line, also keep the barrier about 2 ft in from the line, so you can reach its outside.
Worked example: a ring around a clumper
Say the ring you mark around the clump is 14 ft across.
- Distance around the ring: 3.14 × 14 ft = 43.96 ft.
- A closed ring made from one piece has one joint, where its ends meet. Add 12 in (1 ft) of overlap: 43.96 + 1 = 44.96 ft.
- Round up to the next 5 ft step: 45 ft.
- The longest piece at 36 in is 70 ft, so 45 ft ships as one piece. Order one connecting kit for the one joint.
Does the edge have to go all the way around the clump?
A full ring holds every side. A straight run holds only the side it's on, such as the pool side. On the open sides, cut new shoots at ground level.
Example: a clump along a pool.
- Say the line on the pool side measures 14 ft, including the part past each end of the clump.
- One straight piece has no joint, so add nothing and order no kit.
- Round up to 15 ft. Each cut is at least 20 ft, so order 20 ft. The extra 6 ft can run 3 ft farther past each end.
For other shapes and longer runs, see how much bamboo barrier you need.
When is a barrier the wrong choice?
- You want the bamboo gone. A barrier helps keep bamboo where it is. It doesn't remove it.
- The bamboo is already past the line. Rhizomes outside the barrier keep growing. Dig them out when you set the barrier. Stopping a neighbor's bamboo at the property line covers how.
Common mistakes
- Trusting a vague label. Without the botanical name, "clumping" on a tag is a guess.
- Judging a young planting. A runner can sit still for a year or two before it spreads.
- Reading no groove as a clumper. The groove marks mainly Phyllostachys. Many runners have none.
- Setting a ring tight around a clumper. Set it outside the clump's mature width, with room to work inside the line.
- Burying the lip. Keep 2 in of barrier above the soil, with no mulch over it. Once or twice a year, cut any rhizome that crosses the lip.
FAQ
Do I need a barrier for clumping bamboo?
Usually not. Clumping bamboo widens slowly from its edge instead of sending rhizomes across the yard. Near a foundation, pool or property line, a firm edge is optional. If you want one, use the 36 in depth, set outside the clump's mature width. If you aren't sure which kind you have, plan for running bamboo.
Is golden bamboo running or clumping?
Usually running, but check the botanical name. The plant most often sold as golden bamboo, Phyllostachys aurea, runs. It usually grows 15 to 20 ft but can reach about 35 ft, so if you can't tell whether yours will stay under about 25 ft, use the larger-bamboo row for your zone. The name also covers a small runner, Pleioblastus fortunei, which stays a few feet tall, and a clumper, Bambusa vulgaris, which usually needs no barrier.
Can a clumping bamboo start running?
No. A true clumper doesn't turn into a runner; its rhizome type comes with the plant. A clumper that "starts to run" is usually a mislabeled runner, or a young runner that has settled in. Yushania is the one to watch: it is a clumper that spreads like a slow runner, so treat it as running.
Why 36 in for a clumper, and not 24 or 30 in?
The 36 in barrier is the only Bamboo Shield made at 100 mil, and a widening clump can put a lot of pressure on a barrier next to it. It measures 200 lbf in the ASTM D4833 puncture test, against 155 lbf at 30 in and 130 lbf at 24 in. Most clumpers still need no barrier.
Is giant timber bamboo running or clumping?
It can be either, so check the genus. Japanese timber bamboo, Phyllostachys bambusoides, is also called giant timber bamboo, and it runs. So does Moso, Phyllostachys edulis. For both, use 30 in in zones 4–8 and 36 in in zones 9–11. Bambusa oldhamii, also called giant timber bamboo, is a clumper. If the tag gives no genus, plan for running bamboo.