We have a large rhodo (~15 feet) that is rather lopsided. It's at the north-west corner of the house. The half looking south and west gets several hours of sun, and has leaves and blooms top to bottom.
The other half (north and east) had several large pine trees in the way blocking any light it could get. Those have been ripped out. There are very few leaves, but there are several big branches. Unfortunately, this is the half you can see when looking at our house.
If we prune the full side, will it encourage more growth to the empty side even though there's less light and less small branches? Should we prune hard, or lightly all over? From the top, the bottom, or everywhere?
We did a light pruning all over on the "full" side and have 4 new whorls of leaves on the "empty" side, but they're all on the same branch.
Pruning and fixing the shape of a large lopsided rhodo
If the trees that were blocking the light have been removed, I suspect that side will probably recover and become a little more full over time, chances are before this it wasn't getting enough light, and things are going to tend to be a little sparse when they don't get enough light. Pruning the full side will stimulate more growth where you pruned, it won't do much for the less full side. If you want the other side to be bushier and have more side branches, you could experiment with cutting it back a little bit--don't take entire branches off, but find a branch and trim the end to just above a node (the little bumps along the branch) and you should get a couple new branches coming off from that point. Then if you want the two sides to look more uniform, you could thin out the fuller side a bit by cutting some branches out all the way back to the main stem/trunk. Or you can leave that side alone and wait for the other side to catch up.