#36. Perlite for Growing Vegetables
Most gardeners are probably aware of what perlite is, where it comes from and why it is used in gardening. For the uninitiated, perlite may look like Styrofoam, but is not Styrofoam. It is actually a unique kind of volcanic glass. It is called siliceous rock and can be heated to extreme temperatures when it expands to as much as 20 percent of its original size.
Perlite contains water molecules that get heated up to boiling and then start to evaporate. This causes tiny holes to form in the rock, which is one explanation for it being very lightweight. When heated to a very high temperature, the normal grayish black color turns to white or maybe light gray.
The following are some of the uses of perlite in the horticultural field.
• Perlite can be added to potting mixes or used as a stand-alone soil less medium to root plants in. Perlite's natural pH value is neutral, which is 7.0 and totally sterile, making it suitable for rooting plant cuttings in. Perlite used as a stand-alone soil-less medium holds the right amount of moisture and provides excellent aeration for the plants. Capable of holding as much as four times its weight in water, it does not turn soggy like soil does. It is also beneficial in that it does not disintegrate like soil will eventually.
• The hydroponic system of soil less gardening makes use of perlite to produce superior crop productions. Added to potting soil, the perlite lightens the mixture, improving aeration and drainage. Using perlite in container gardening is very beneficial to the plants in terms of moisture retention and drainage.
• More recently, perlite is being used in rooftop gardens. When there is absolutely no space on the ground, man goes to the roof to garden. The main problem for rooftop gardens is the weight of the soil. Because perlite is practically feather light in comparison to soil, it is a good choice. It actually reduces the weight by more than half, making rooftop gardens thrive.
• Plant nurseries are very glad to have perlite; it dramatically reduces the cost of shipping because of its light weight. Further, plants continue to remain in good condition until they reach their destination.
One concern about perlite, was whether the fluoride content in the perlite was being absorbed by the plants. This may be a cause of possible toxicity for the plants. However, studies have shown that perlite did not increase the fluoride absorption of plants.