The bamboo barrier we recommend is an extremely tough, flexible plastic, used for a variety of industrial uses. We cut it to whatever length you need.
When installing HDPE bamboo barrier (high-density polyethylene) first measure the area to be contained so that, ideally, you can encircle your bamboo with a single sheet. Then dig a trench the depth of your barrier around the site. If you're planting a small area or a narrow row of bamboo for a screen, it is best to dig all of the soil from the planting area, digging the edges of the hole about four inches deeper than the rest, and place the barrier material vertically around the perimeter of the hole. We recommend leaving two or three inches of the barrier sticking up above the ground to keep the bamboo from escaping over the top and allow for settling and mulching.
The barrier needs to be secured where it is joined together to keep the bamboo from slipping between the plastic sheets. Although it is recommended to overlap the sheet one foot at the joint, just overlapping the barrier is not any assurance that the bamboo will be contained. Some gardeners use duct tape to prevent bamboo roots from escaping.
Fill the trench with the soil you removed, being careful to compact the soil next to the barrier. Do not add any amendments to lighten soil in the bottom next to the barrier. This is very important as you must discourage the rhizome from going deep, and possibly going under the barrier. Bamboo rhizomes are usually in the top few inches of the soil, but when they reach the barrier they will turn. If they go down and encounter loose soil or air pockets, they may go deep, and perhaps go under the barrier.
When installing the barrier it is important not to make any sharp curves in it, as this could encourage the rhizomes to turn down. If your planting is square or rectangular, make smooth curves at corners if possible. This will make containment more sure. You should check every fall to see if the bamboo has escaped over the barrier. If any rhizomes have crossed over the top, just cut them off.