[sandworm101]

You dont plant tree seeds by hand. You plant saplings, small trees well past germination.

[vanattab]

Well presumably someone is planting the seeds for the saplings unless they are all clones.

[dymk]

That's called a tree nursery. Seeds are planted and germinated in controlled conditions on a few acres.

Once they're baby trees, then you go plant them by hand in areas that need reforestation.