Whenever this topic comes up, so does the question of rhizome barrier. After years of listening to escape stories, talking with other growers, and observing “contained” bamboo, I am convinced to the marrow of my bones that a vigorous running bamboo will defeat a poly rhizome barrier over time, every time. I will save further commentary on poly rhizome barrier for a future article, except to say that the best way to contain a running bamboo is by religious rhizome pruning.
Tools
You can use a variety of tools to rhizome prune. For really big groves a tractor with a tilling attachment works well. For smaller groves with less room to manuever, a walk behind tiller works well. For most of my work, however, I use a mattock and loppers.
Techniques
Most bamboos have a shallow rhizome system, so you can use the “pointy end” of the mattock to scratch through the top 6″-8″ of soil at the edge of the bed. When I encounter a rhizome, I make sure the pointy end is underneath the rhizome, and then I use the flat end of the mattock for leverage to pull the rhizome up out of the soil. Then with my loppers, I snip the rhizome, and pry up the rest of the rhizome, and remove it from the soil.
Timing
Rhizome pruning is a fairly easy job if you are religious about it. If you get behind on your pruning, (like I did in the pics above) you will have to wrestle with some long woody rhizomes, making the work a lot harder than it needs to be.I recommend doing it 3 times a year; once in July to get rhizomes while they are still young and easy to snap off; once in October after the rhizomes have finished their growth for the season; and in spring, to get any rhizomes you missed. If you missed any, you will see new shoots that will point you to the offending rhizome.
Depending on where you live, you may have to adjust the timing to catch the rhizomes before they grow too far out of the bed. As long as you rhizome prune religiously, you don’t have to be afraid of your bamboo!