I'm interested in planting bamboo in my yard. How can I keep it from spreading?
I have recently purchased a newly built home, and I am starting to landscape. I've planted several maple and redbud trees around the house and will be adding several bushes along the side. I will also be adding several birch trees and making my own garden this fall. I was reading up on bamboo and became interested due to its fast growth and hearty nature (it can survive 100-degree summers and cold winters). However, I am concerned as to how best to limit the bamboo from spreading outside the area I've planned. What is the best way to plant bamboo and prevent its spread?
Bamboo is a vastly misunderstood plant. It is soft and flowing, and at the same time it's considered highly aggressive. In fact, in order to plant bamboo in Tokyo, you have to get written permission from your neighbors because of all the experiences folks have had with bamboo disrespecting property lines.
There are two strategies for dealing with bamboo that work and a third one that is only as effective as the gardener.
The first strategy is to select a species of bamboo that's considered non-invasive. Remember that in general, bamboo species can be divided into "runners" and "clumpers." Clump bamboos are considered non-invasive and are easily removed and/or transplanted. Of course, clump bamboos are much slower growing, which means you will need to use a lot more of them if you want to use this plant for screening.
The second approach applies to dealing with the "runners," or the more aggressive species of bamboo that spread by sending out runners or rhizomes. Some can be well-behaved in cold climates, but most, when in a warm climate, and given plenty of water, can become a serious problem. Don't plant a runner in a small yard in a warm climate unless you put a rhizome barrier around it.
Barriers must be at least two feet deep but preferably three. They can be concrete, plastic or metal. The barrier must be completely enclosed, essentially forming an underground planter wall around the plant. The least expensive are generally high-density polypropylene (HDPP), 40 mil or heavier, clamped with stainless-steel clamps at the junction. They must be sealed tight where the beginning and end of the HDPP walls meet or the rhizomes (the runners) will slip between the cracks. It is also recommended that the walls slant outward at the top of the enclosure so that rhizomes are deflected upward, making them easier to prune and manage.
Finally, it is possible to manage bamboo by going after the runners, or rhizomes, as they travel. Start by cutting the connecting rhizomes, which are usually quite shallow. If you don't, and the original rhizome group is healthy and vigorous, the rhizomes you want to eliminate will still be supported by the photosynthesis in the leaves of the main group even if you cut the "culm" or canes to the ground in the area you want to keep bamboo free, and your efforts will be in vain. Cutting rhizomes with a spade or a saw will do the trick if you do it every year. If the growth is old, you may need to use a mattock or a digging bar the first time.
Even in colder climates, once the runner varieties become established, they can become very aggressive. I have some Nigra bamboo in zone 5 that is pushing its way under retaining walls and growing through existing shrubs. Once this sort of thing happens, it can be difficult to remove the runners without damaging the shrubs.
More information on bamboo species, managing bamboo, and suppliers of barriers and other useful products can be found at the American Bamboo Society website.