can't find the tree capsule anywhere

Hello, have you unlocked the "tree seeding" tech ?
I just pushed a new version, please update and tell me if you still have the issue.

There was a bug that made it so that, if you had already researched the technology, the recipe would be unlocked.
However, it would not unlock it if you installed the mod, then did the research. You had to reload the game.
This is now fixed, it was an oversight on my part, I confused the name of the tech with the name of the recipe for wood processing.
Updating the mod and loading your game should fix your issue.

Thanks!

Can there be an option to have this unlocked at an earlier stage?

That would change the purpose of the mod.
The goal of this mod is to let you use a lot of tree seeds using blueprints, and to integrate into the flow of Space-Age.
Unlocking it at an earlier stage would defeat this purpose.
You cannot plant trees anyway unless you have researched the tech unlocking it.
I will consider adding options to make it possible in a future release, but don't get your hopes too high.