Our 3/8"+ - 1/4+" pumice is ideal those wanting a clean hand screened pumice of a larger size for soil mix's or to improve the drainage of water sensitive plants. Our pumice is a natural volcanic product mined in the Southern Cascades Mountains of Oregon. You get only clean pumice... no rocks, roots or other debris. Known as the "rock that floats", pumice has many tiny gaps or air pockets that allow roots access to oxygen, nutrients and water. Pumice improves both water retention and drainage of your soil mix. We ship our pumice by Priority Mail in boxes that are a little larger than the standard large flat rate square box. Our pumice is hand packed and bagged with a reusable tie for easy storage after you have used part of the bag. If your pumice dries before using, moisten it to keep dust from forming. Dust from any rock or potting soil product should not be inhaled and can be irritating for people with sensitive lungs. Our box contains 830 cubic inches or over 3.5 gallons liquid measure, or will fill 7 -- #1 horticultural containers with pure pumice. Mix in 15% pumice into a soil mix for general horticultural use including Japanese maples, raised beds and containers. For Daphne, Monkey Puzzle trees, Franklin trees and other plants that are water sensitive use 30% of pumice to mix. For cactus and succulents add 60 - 80% of pumice to 20 - 40% organic matter. For Bonsai soil mix use 33% pumice, 33%course compost or bark and 33% black lava or sand. Pumice can not be combined with other items for combined shipping. Scenic Hill Farm is a licensed Oregon nursery -- license # L0170090NG. +