A small mod adds craftable saplings that grow into vanilla trees, and a tree farm for producing wood directly.
This mod is originally written by LukeM. I take no credit for the code or resources within, and only wish to maintain it in their absence under the original MIT licensing, because it's an awesome mod.
If you're just looking for wood, may we suggest Bob's Greenhouse mod
None of the original code has been changed as of the 0.3.0 release, only the json file which prohibited loading. If you find any issues, please let me know, and I'll work on getting them fixed as time permits.
LukeM if you happen to come back, I'll gladly release any code changes back to you, and retire this "fork" version.
Extended credits go to Shrooblord for the sapling and fertilizer item textures
and to Fusselwurm for the German localization