Plain soil from a garden can weigh 12 lbs per 1 gallon. Add water, which weighs 8.3 lbs per gallon at room temperature, and also a large container can develop into an immovable item. Soilless potting mixtures, based on their composition, can weigh a few ounces to 1 pound per gallon. Their lighter weight and receptive texture keeps moisture and allows pot-bound origins to stretch and breathe.
Potting Mix Contents and Measurements
Potting mixtures are composed variously of coir, peat moss, humus, compost and soil conditioners such as vermiculite or perlite in combinations intended for successful container gardening. Potting mix bags typically record contents in quarts or cubic feet, not gallons. So comparing contents from gallons isn’t quite as accurate as with the other dimensions. 1 gallon, however, is equivalent to 4 quarts or roughly one-sixth of 1 cubic foot. Soilless potting mixes may vary in weight from 16 oz to 117 oz for 4 quarts.
Mix Composition and Weight
Commercial potting mixes vary widely in composition, and also the materials’ dry weight contains moisture from environmental humidity. A mixture based on coconut coir, which weighs 11 1/2 oz a 1 gallon, weighs less than a mixture that contains peat moss, which weighs 60.8 oz per compressed gallon. General mixtures heavy in vermiculite or perlite that chew oz per gallon weigh much less than cactus mixtures containing mud, which can weigh over 160 oz per gallon. For general usage, however, a lighter potting mixture provides better moisture retention and also allows drainage for extra water.