Once a bamboo culm(stalk) is cut, it will never grow taller, it will remain at that height though some of the limbs may grow a bit higher.

Next years culms will grow as tall as the ones you cut last year before they were cut back, maybe even taller depending on a few factors, so you need not worry, just might have to wait until next shooting season.

Kt

should i remove the culms that are thickly short so that the new shoots have room to grow high?

No, I wouldn't, at least not until the new shoots are grown and leaved out, otherwise you will be taking away the growth that helps produce food for the new culms/roots/rhizomes.

Kt

is there a fertilizer that i could put on the bamboo to help it grow faster this spring? or is sun and rain the only hope?

A cup of standard grass fertilizer may help a little in the spring, but it will not give you hugely different growth than what will occur naturally. Either give it some fertilizer next year and then let it do what it is going to do, or just let it do what it is going to do. At this point, there is little more you can accomplish by fiddling further with it...at least of a positive nature.

This post was edited by kudzu9 on Fri, Dec 21, 12 at 19:04