Used in agriculture before the days of ancient Rome, pumice continues to be an ideal growing medium to this day. Uni-Gro Pumice has a variety of characteristics making it useful throughout your garden. Providing excellent aeration to the soil, it loosens heavy clay soil and retains moisture well. It won't break down, compact or rot, giving your roots the space they need. Along with these characteristics, Uni-Gro Pumice will also make it easy to control nutrients; will not provide a host to fungi, nematodes, insects, etc; is easily leached; has a neutral pH; and does not give off any offensive odors.