Giant oaks grow from robust saplings- nearly impossible to get legit (I think its only as dungeon loot- like 4x less than a golden apple).
But yeah- bonemeal works on them. (They also have a very aggressive growth pattern)
-Canopy trees must be bonemealed, or you get something different.
Redpower saplings are a single sapling in a flat 3x3 of dirt- with something like 15x15x15 minimum space needed. Usually takes 2-10 hours real time, and I cant grow them on top of a desert mountain- so there might be a biome/y128 limit.
Anyone tested the thaumcraft hoe on them?
Forestry/vanilla saplings can be put through a treealyzer to get all the growth info.