If you're battling an insect infestation in your garden, try this nontoxic tip: Save your bathwater. The residual soap in the bath water is both an insect repellant and a natural fungicide for plants. Just be sure to bathe using natural and organic bath products. If you soak your aching muscles using Epsom salts, save that water, too. The magnesium in the salts promotes plant growth. Just allow the water to cool completely before using it on your plants.