I recently began learning to fly fish. However most of the streams I frequent are small creeks in the Southern Appalachians that have a lot of growth on the banks and overhead making casting rather difficult.
Is there a particular cast technique that works best when you have little room in the back or on the sides? So far I've learned about rolling cast, are there better alternatives?
I have found the side cast, and here, to be very useful in the situations you describe. I spent a number of years fishing small streams in the Blue Ridge of VA, and this type of cast gave me better reach than roll casting.
I also favored a 6'6" rod in 1 or 2 wt. The short length of the rod kept me out of a lot of overhanging vegetation, but it also limited the distance I was able to get from roll-casting. The side-cast doubled or trebled the distance in many instances.
Another good cast for small streams with lots of bushes is the water haul, described in this blog post at Gink and Gasoline. It basically uses the water tension to load the rod, like the roll cast, but you cast towards the opposite direction from where your line is lying (no d-loops). You start with your line straight downstreams, which creates the tension, and flex your rod towards your target (upstreams or across the stream) allowing your rod to bend and unload propelling the line. I suggest you watch the video in the post linked above, as a (moving) picture says much more than words.
The bow and arrow cast is also effective, you can't cast very far but that's generally ok when there is a lot of vegetation to hide behind
"Flipping" is another option. It is for close range fishing with the maximum distance you can "flip" around a rod length. So it works well with long rods. You definitely need some weight in the rig as you're essentially dropping the fly and swinging it into place.
Explaining it in words is too hard for me. See this video from Tom Jarman for a great demonstration Casting Nymphs Into Tight Pockets
