With spring around the corner, your outdoor window boxes and garden pots may still have last year's potting soil in them. So the question is: Is it any good? Or if you are repotting a household plant, can you reuse the old soil? The answer is no, unless you know for sure the soil is free of any disease. Since that can be impossible to tell, the best way to reuse potting soil is to sprinkle it in the yard, where the sun will have a chance to "bake" the soil (killing any disease), and it can blend into the ground.