Perlite is a naturally occurring mineral that is added to garden soil to improve aeration, water retention, and drainage. It looks like small, white Styrofoam balls and is commonly found in potting soil and seed-starting mixes. Gardeners often use perlite in vegetable gardens and flower beds to improve water drainage and aeration.
 
In its processed, lightweight form, perlite offers many advantages as a soil additive.
 
Perlite has a neutral pH level, gardeners can mix it with their soil and not worry about it changing the soil's pH level.

Because it's made from naturally occurring compounds found in the soil, it contains no toxic chemicals. This also makes it a top choice for organic gardening.

Once processed, perlite retains its shape, even when pressed, and is physically stable. This makes it great to use in clay or compacted soils.

In its processed form, it's very porous. When added to soil, it improves aeration, water retention, and drainage.