How to use

1. Pick a plant, then click its square in the grid.
2. Drag the block, plant or arrow until the arrow tip is where the plant stands in your screenshot. The cross is the middle of the block.
3. Do this for 4 or 5 plants. Right click or long press a square to take its plant away.

Blocks and Bedrock work the same way: pick a block or tool and paint the squares, one layer at a time.