Have you ever wondered what those little white things in your potting soil are? In most instances they are perlite and/or pumice. Perlite is a mined siliceous rock that is expanded, similar to microwave popcorn, into a white lightweight material, while pumice is a soft insert-mined stone that often comes from Oregon. What makes Black Gold® Perlite and Black Gold® Pumice particularly desirable is both are screened for uniformity, with the finer particles removed.

Both perlite and pumice are called aggregates, meaning they are added to a potting soil to improve aeration and drainage. The addition of perlite and pumice in a potting soil will also increase the moisture and nutrient retention of the potting soil. Just like peat moss, they act like reservoirs in retaining water and nutrients when these items are in excess and releasing them when they are needed by the plant.

Due to its weight, pumice can provide bulk density to a potting soil. This trait is valuable when you are growing outdoor containers and you don’t want them to blow over in the wind. Pumice is often the aggregate choice for specialty potting soils (cactus, bonsai) because it provides great aeration and an anchor for the roots.

In addition to being a potting soil mix component, perlite is an excellent sterile medium for starting seeds and rooting cuttings. Perlite can also be used to store bulbs and as a Hypertufa planter ingredient.

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