Qualities of Perlite

• Perlite is made from volcanic rock that has been heated to expand the particles. This makes the perlite light and porous. This material keeps the roots of plants well-aerated. Perlite absorbs a fair amount of water but is primarily used in mixes such as potting soil for its good drainage qualities, not moisture-retention abilities. It does, however, offer another very valuable quality for mushroom growers. Perlite has a larger surface area than vermiculite, so more water evaporates from it. This makes it a useful material for adding extra humidity to the growing atmosphere.
  
  

Qualities of Vermiculite

• Vermiculite is a mineral that is also expanded by heat treatment. This material also keeps the roots of plants well-aerated. Since vermiculite absorbs more water than perlite, it retains more moisture next to plant roots and also takes in nutrients, releases them to plant roots and keeps the nutrients from washing away. This sponge-like quality makes vermiculite ideal for adding extra moisture to the soil mushrooms grow in, but it does not add humidity to the growing environment.
  
  

Using Both Vermiculite and Perlite

• Vermiculite makes the best addition to the soil base for growing mushrooms because it ensures an adequate water supply in the soil next to the roots. Using vermiculite doesn't mean you must forego the benefits of perlite. Since mushrooms are made up of 90 percent water, it makes sense to keep the humidity in their growing environment as high as possible. Keeping humidity high can be achieved by cool-mist humidifier systems, which are expensive, or frequent hand-misting with a water spray. A third method involves soaking perlite in a bowl of water, straining the mixture and then layering it an inch deep on the floor of the growing area.
  
  

Purchasing Perlite and Vermiculite

• Since these two varieties are used interchangeably in potting soil recipes, stores often carry one or the other. It is important to know which you are buying because of the different qualities of each type of soil additive. Store assistants can offer to sell you perlite as vermiculite or vice versa and tell you that they are the same material, according to worldseedsupply,org experts. While it is true that these two varieties share many qualities, a mixup can destroy the batch you are growing. Carefully examine the bag for the name "perlite" or "vermiculite" to ensure that you are buying the product you need.