if you are truly in zone 5, i don't think even 20 feet is a realistic expectation for you, 35' is the max i expect here on the cold edge of z6, 25' after 6 years is the max thus far.

Yellow groove bamboo will grow well for you there, I have it too, but it doesn't get that tall. Can you plant it closer to the house, towards the top of the hill? Then it would still do a good job for you, and you could wait for the pines to fill in at their own pace.

The ultimate size attained by Yellow Groove (Phyllostachys aureus) depends on your zone and other climatic factors (light, rainfall, soil, etc). So the sizes that you see given for these species are not necessarily exagerations. Also, keep in mind that it may take a several years for the groove to get established. Lewis Bamboo (boo nursery in Alabama) gives the following as an approximate guide to eventual heights depending on zone:

Zone 4 (8 feet)
zone 5 (12-14 feet)
zone 6 (18 feet)
zone 7 (40 feet+)

Sometimes posters make general statements about the performance of species in their own backyards without realizing how different the same plant may behave in another area. PS.: In my area, I would never plant P. aureus in the ground without serious attention to rhizome control (speaking from personal experience here).

Hello I am also looking for tall bamboo. I would prefer a variety that does not go everywhere. Any suggestions? I have a island in the middle of my pond and was curious if bamboo would makes its way across the pond? If it would stay on the island that might work.

how big is the pond?

My pond is 80' x 30' and about 10 feet deep. The island is in the middle and is about 8' in diameter.

I'm going to go out on a limb and say that I would find it unlikely that bamboo would escape your island....Assuming that the water table doesn't drop significantly for long periods of the year...

~Chills