How do you put seeds in a planter?

You need the planter, a trowel, and either seeds or the fruit/vegetable. You also need to have read the gardening textbook.

I think a lot (read: most) hydrocraft seeds aren't usable. You're supposed to plant the planter in the sowing menu but most of the seed types are missing from the list.

Super disappointing, I wish someone would fix that.

I can only tell you how it was in Build 40. I dont have access to planters yet in my playtrough. In the Build 40 version, crops that are in a planter would grow automatically.

After 6 days most crops are ready for harvest. Some plants can only be harvested once and have to be re-planted. Other plants like apple trees, lemon trees, orange trees (all kinds of trees and bushes) can be harvest more than once, because the fruits grow back after 3 days.

This was / is of course pretty powerful. So now they changed it to something more realistic, by nedding to sow the planter as a seed.

But there are still MANY plants missing in the "sow seed" option. So I guess some planters still work the old way. Or maybe they disabled the growing of planters. I cant say for sure cause im not there yet xd