1cm MAX.
A good rule to follow for planting any seed is bury it below a depth of soil equivalent to 3x its diameter.
By that calculation, you'd bury a cannabis seed about 6mm but an acorn would get planted 2-1/2 inches
stinkyattic Reviewed by stinkyattic on . Depth of seeds After germination, when the seeds have little tails ;) How far in soil do i plant them? IE How far down? Just below the surface 1cm or like a good 5 cm under ?? Just dont want a lanky sprout, i want them to be short stubby fat plants. cheers Rating: 5