Keyboard: 1, 2 or 3 picks a stack from the tray. Arrow keys move between spaces. Enter places the stack. D describes the garden. L lifts a stack off the board. N gives new stacks. U undoes.
Your garden is saved and will wait for you.
No empty spaces are left for these stacks. You can undo, lift a stack off the board, or start the level again. Nothing is lost.