Critics will tell you not to plant bamboo because it’s invasive and uncontrollable. Yet many gardeners are able to grow bamboo with great success and minimal disruption. Of course, the more you know about bamboo, the better your results will be. And it always helps to have the right tools for the job.
When it comes to maintaining and containing an orderly grove of running bamboo, a reliable bamboo root barrier is essential. Not all varieties of bamboo have such vigorous and aggressive root systems, but those that do will require an effective containment strategy. Unlike many makeshift devices, Bamboo Shield root barriers, made of HDPE (High Density Polyethylene), are deep enough and sturdy enough to keep bamboo rhizomes in place without degrading.
How bamboo roots and root barriers work
Rather than a primary tap root that runs deep under most trees, bamboo is grass with a shallow network of sprawling rhizomes.
Some bamboo varieties, known as clumpers, maintain very compact root systems that tend not to spread very far. Usually these clumping bamboos prefer warmer climates with tropical or subtropical conditions.
Alternatively, there are temperate bamboos, also called runners, whose roots and rhizomes will spread and expand almost indefinitely. These bamboo species are far more common in most of the United States, Europe and Canada. And these are the varieties you need to be careful with.
Without the proper equipment and know-how, these running bamboo species may appear impossible to contain. The more you dig and prune, the more tenacious and insidious the roots become.
That’s why serious bamboo gardeners and those who install bamboo professionally insist on planting a rhizome barrier around the grove. And experts agree that Bamboo Shield makes the most effective and durable barriers.
Made in the USA from High Density Polyethylene (HDPE), these 2-3 feet wide and 1.5-2 mm thick black bands will hold up against the elements and the forceful pressure of subterranean bamboo.
The heavy-duty material comes on rolls from 15 to 80 feet in length. That should be enough to protect your neighbors and the rest of your garden from the encroachment of bamboo.
Selecting the right sized bamboo root barrier
The wide range of sizes can be somewhat confusing and intimidating. It’s essential that the barrier is deep enough to keep the bamboo in place. Although the bamboo roots are fairly shallow, they will burrow downward when they run up against a barrier. It also helps to let the barrier stick up a few inches above the ground. Otherwise the rhizomes can easily leap over the barrier and exploit the unprotected landscape.
So even though the roots are only about a foot deep, you should really use at least a 30″ deep root barrier that’s 80 mil thick. Just so you know, a “mil” is a thousandth of an inch, so 80 mil is about 2 mm. In most climates and soil types, this size barrier will be sufficient.
But if your plants are in sandy soil or growing in a warmer or wetter climate, you’ll want something more heavy duty. Bamboo Shield also makes a 36″ deep root barrier that’s 100 mil thick. If you really want something indestructible, for timber bamboo, for example, then this is the way to go. You can expect these heavy barriers to last many years. In fact, professional landscapers report that they’ve never seen one fail in 20 years of experience.
As a lighter and less expensive option, they also make a 24″ barrier with 60 mil thickness. These are a good choice in rocky soils where you can’t dig that far, and for smaller, dwarf bamboo varieties.
In terms of length, the smallest option is 15 feet, and that’s probably only meant to cover one side of a grove. If you wrap the 15′ barrier in a closed loop, you end with a circle less than 5 feet across. That’s a pretty small grove, and anything larger than a dwarf variety could start to get cramped in.
Installing your your bamboo root barrier
It order to reap the benefits of a reliable rhizome barrier, you’ll need to put in a little extra sweat and toil on the front end. Even if you hire your neighbor, or your neighbor’s kid, to do the grunt work, you’ll want to have the right tools on hand.
The HDPE is strong and virtually indestructible, but you can’t just hammer it into the ground. You’ll need to dig a narrow trench where you can sink the barrier, or at least 90 percent of it, and then pack the dirt back in around it. A good trenching shovel will be your best tool for this job.
If you’re thinking of cutting corners and not spending money on a root barrier, you’re not alone. It’s been tried. And sometimes it works for a few years. But eventually the bamboo prevails, and you end up with a mess.
Plastic drums look like an easy solution, but they have problems. The plastic is usually not thick enough, but if it does hold up, the small space is likely to result in root bound bamboo. It’s difficult to take cuttings out of drum, so the roots will probably get bound up and strangle themselves.
Metal barriers seem solid, but underground in wet soil, the elements take their toll. Whether it’s aluminum siding or stainless steel, it will eventually degrade and leave you with an awful clean up job. Aluminum roll flashing is a popular option, because aluminum does not rust. But it will corrode, and eventually the bamboo rhizomes will get through it.
Many gardeners will recommend above ground planting, in a raised bed over a slab of concrete. In warmer climates this is a viable option. But in colder climates the bamboo won’t like it. The roots keep warmer, happier and healthier underground, insulated by Mother Earth.
In the end, if you want to enjoy a healthy, flourishing grove of running bamboo, you will need a strong and durable root barrier. Sometimes a trench works too. You can also get great results by planting barriers on three sides and digging a trench on the fourth side. Refer to this article on how to dig a trench around your bamboo.
If you want to learn more about maintaining a healthy bamboo grove, check out some of these related articles.