Choose a location in the yard for the garden tub. Remove any debris from the area. Pull out weeds or spray weed killer.
Place the old bathtub in the yard. You will need a few people to help you carry the tub.
Put a stopper in the bathtub drain. Apply plumber's putty to the edge of a plastic putty knife. Place the edge of the putty knife against a side of the stopper. Press down on the knife as you pull it across the stopper. Repeat this procedure until the stopper is completely covered with plumber's putty. Let the putty set for a day.
Fill the tub halfway with potting soil or garden soil, depending on the types of plants or flowers that will be planted. Smooth the soil with a hand rake.