In full sun most groundcovers will curl their leaves and look really sad. Even in part shade they will suffer in the Summer heat. The best thing to do would be to keep it watered and shaded. Maybe you could put a shade cloth over the bamboo like they do with roses in the southwest.

It will stay the same size right now until spring when it shoots.

Thanks Brian, but it's been in the ground for several months, maybe as many as 10! and hasn't done much from the start, started in more shade..but not deep..now in sun..:>P D

Debbie,
I think I bought the same from Wayside three years ago. I put it in full sun next to a pond with some larger plants for shade. It is still only 4 inches tall barely growing at all. I just moved it to full shade against a building. I think this bamboo needs lots of shade and no competition. Check with me next spring and I'll let you know if this works.
Jennifer in Kentucky