This is a wonderful species, in my opinion!
It will grow large, however, which brings me to my first suggestion:
if you want a truly mini-grove, you might prefer a mini-bamboo variety.
I don't want to discourage you from Black Bamboo, I just want to be clear
that it will require maintenance in the given area.

I am developing a nice grove, as well, but not in such a small space.
A 4' x 8' area will be filled within 3 - 5 years....but you'll have to trim/tend in the second year for sure.

The culms emerge green, and darken over 3 years or so. A bit of shade will help them darken faster.
The mature culms last for about 7 years.

As the grove ages, I would selectively thin the culms, keeping mature culms about a foot apart from eachother.
You might have to remove sections of rhizome, too, if the area becomes congested.

If you're prepared for the maintenance, go for it!

Josh

How is your mini-grove doing? They are definitely doable and less invasive as many people tend to believe. Sometimes we sort of have them in a raised bed or on a bit if a slope (ie. a ditch) which naturally prohibits the roots from spreading. Another option is going with a sheet of polyethylene plastic and burying it about a foot down. Bamboo roots stay more on the surface and tend to try to go around rather than under something.

Here is a link that might be useful: Bamboo Gardening

Hi Greenman28,
"The mature culms last for about 7 years."
Are you saying that the canes die every 7 years or so or that they stop going & die at a later time?
Do all bamboo live the same length of time?