This achievement is first available after you've grown your star plant to its maximum height, and it has bloomed in outer space (as plants do). M.O.M. will instruct you to take the seeds that appear at the top of the plant and teleport them home. There may be more efficient ways to do this, but for me, I climbed to the top of the plant and just grabbed one of the seeds (L2 or R2). From there, I did a high-dive to the ground, holding on to it the whole way down.
Don't deploy your flower parachute or leaf glider to slow your descent until you're certain your star seed won't land in the water, because you'll let go of the seed as soon as your flower/leaf is deployed.
Once you and the star seed are safely on the ground, simply grab it again and drag it on to a teleporter and let go. The trophy should pop once it's been registered.
Please let me know if any of this is unclear in the comments