What is Perlite?
Perlite is a generic term for naturally occurring siliceous amorphic volcanic rock. But unlike other volcanic glasses, it expands from 4 to 20 times of its original volume when heated above a point (800-900 deg C). Perlite is mostly made of silica or SiO2 (about 70-75%). The rest is the mixture of Aluminum Oxide or Al2O3, and Oxides of Sodium, Potassium, Iron, Magnesium, and Calcium, and moisture.
Perlite is mined throughout the world. Countries like Greece, USA, China, and Turkey are the forerunners in this.
When perlite is heated above 900 deg C the moisture trapped inside the rock vaporized and escapes and causes the huge expansion of the material. After the expansion, the bulk density of the perlite reduces significantly (0.03-0.15gm/cm3). The expansion also creates the most distinguishing feature of perlite its white color. While the unexpanded perlite rock may range from transparent light gray to glossy black, the expanded perlite ranges from snow-white to grayish white.
Because of its low density and low price, perlite has many commercial applications. Among which main uses are building and constructions use, horticultural uses, filters, and filter aids. In gardening and horticulture, perlite is used for a number of reasons.Apart from gardening perlite is also used in building and construction works Click To Tweet
Advantages of Perlite soil in gardening and horticulture:
Perlite encourages quicker germination than any other growing media with quick seedling growth. It can be used by mixing with peat moss or coconut coir and used as a potting mix or it can be used solely provided it kept wet all the time.Perlite are almost pH neutral. So it doesn't increase the acidity of the soil. Click To Tweet
Perlite is inorganic, inert and sterile. It naturally contains the different minerals which are essential for the growth of the plant. Being inorganic it is free from weeds, diseases, and pests.
Perlite is non-toxic and there are very few fire hazards.
Unlike peat moss, perlite does not decompose very easily (if at all) so you can store and use perlite for many years.
It improves aeration and drainage of the soil mix if mixed with other growth media, or soil.
Perlite is almost pH neutral. So it can also help to reduce the acidity of the soil.
Disadvantages of perlite soil:
There are a couple of disadvantages also of using perlite as growth media.
Perlite holds water by having a large surface area and within the nooks and crevices of vast pores. But being porous and made of volcanic glass it allows the excess water to drain away much quicker than any other media. So in case you have really thirsty plants, investing in perlite might not be a good choice.
Perlite is a non-renewable resource. Which means you can not increase its availability as per your likings as in the case of coconut coir.
Other Perlite Uses:
Perlite as an excellent filtering agent. Besides horticulture, Perlite filters are used in many places to filter beer before getting bottled.