Contact Gib Cooper at Tradewinds Bamboo Nursery in Gold Beach, OR He has a website and you can call or email him. He can answer all your questions about barriers and how bamboos do in your area.

Here in Texas, black bamboo is one of the fastest runners. I planted a 1 gallon pot of black bamboo one Spring, and by mid to late summer, it put up a shoot over 15 feet from the original planting. It was the bamboo that made my decision to install barriers.

Gold Beach Oregon is over 260 miles away from me. I have contacted a couple different nurseries that specializes in bamboo and the problem that I have found is that they don't want to give out the information unless I'm going to buy the product from them or have them install it. One bamboo nursery told me "because every different installation of bamboo is different, we need to visually look at the area you are wanting to place the bamboo and determine what is best for your situation" which is just another way to try to get me to go with there product and service.

When in doubt, go with the thicker barrier :-) I'd choose the third both because of the thickness and the additional depth to work with.

IME in the Puget Sound area, black bamboo tends to be a rather slow spreader.....in fact, many believe it to be more of a clumper than a spreader and some folks can get by without any barrier system if they are diligent about pruning out wayward culms. This is also one of the reasons black bamboo tends to be so pricey here......just takes some time to mature into a significant clump!! Make sure at least 4" of barrier is exposed above grade to limit any culms "jumping" the barrier (although personally, I doubt you need to worry much) and there is adequate overlap at any joints in the barrier.

As I said before, talk to Gib Cooper on the phone or email him. He will be happy to help you and can sell you the barrier if needed, postage paid. He is the authority on bamboo and was the president of the American Bamboo Society for many years. He will be glad to help, even if you do NOT buy from him. You can save time and talk with him, or spend hours looking and searching websites and still leave confused. Your choice.

And just so you know, all bamboos will respond and grow differently in different areas. I installed 6 barriers, all approximately 9' X 27' and all failed within a few years. However, keeping the remaining bamboo in check is easier with the barrier then it would be without it, but they all did fail.

I grow about 70 different kinds of bamboo, and many of my runners, including black bamboo, are enclosed by barrier. I use 60 mill, 24 inch barrier and install it with about 2 inches exposed aboveground. I make sure that I don't put any sharp rocks back in the trench when I fill it in. I overlap the ends of the barrier by about a foot and make sure no dirt gets in between by duct taping the barrier ends. I've only had one instance where a rhizome sneaked out between the overlapping ends, and that was pretty easy to deal with. Otherwise I've never had a failure of barrier in the 10 years I've been using it. However, as kentuck points out, if there was a failure, it would be a lot easier to deal with because of the barrier. My growing conditions are pretty similar to yours, Seth, as I live in the greater Seattle area and my growing zone is the same as yours.