What is Perlite and what is it used for?
That’s the question many amateur gardeners often ask. Well, Perlite is a naturally occurring, silica based volcanic rock, which has a high moisture content. During the manufacturing process, the rock is heated to a very high temperature (1,650°F - 899°C), which causes it to expand as the moisture content turns to steam and escapes. The rock particles then swell up to many times their original size, similar to popcorn. What is left is an exceptionally light and porous material, which is stable and sterile, and resembles small polystyrene foam balls.
What is Perlite used for?
In horticulture, Perlite is used as a medium for the propagation of cuttings, potting mixes, as a general soil conditioner and to aid the breakup of heavy clay soils. Its unique properties include water retention, which is highly beneficial to growing plants in pots, which tend to dry out very quickly. Perlite is particularly useful when growing plants that require high humidity. It is also used a soil conditioner. Heavy clay soils for example, do not drain well and therefore would benefit from the addition of Perlite, which will help to “open” the soil, allowing water to drain and more air to penetrate. Aeration and drainage are very important in all types of soils and growing composts.
What are the benefits of using Perlite?
Primarily, the benefits of using perlite are the increase of both moisture retention and aeration. When added to seed or potting compost, Perlite will speed up seed germination and improve seed growth and health. Mixed at a rate of one part Perlite to one part potting compost, this medium will help plants to grow and become established much quicker. Cuttings, especially soft tip cuttings need to be “struck” quickly, otherwise they can rot and die before they have a chance to grow new roots. Adding Perlite to a cutting compost can significantly improve the chances of successful root growth.
How Perlite works
Overwatering can often cause problems with young plants or cuttings rotting at the base, or “damping off” as with seedlings. Seed germination failure can be quite high, especially when conditions such as wet compost, cool temperature and poor drainage are evident. However, the increased aeration and drainage that Perlite offers, ensures roots grow quickly and healthily. By adding Perlite to seed and potting compost, the medium becomes more “open” allowing water, air and warmth to circulate much more effectively. Young plants will therefore thrive in a compost that offers these favourable conditions.
Summary
Why you should consider adding Perlite to your soil, seed and potting composts.
- Prevents soil compaction
- Improves aeration and drainage of soil and composts
- Stimulates root initiation and promotes vigorous growth
- Retains moisture but does not become soggy or saturated
- Insulates and minimises temperature fluctuations
- Organic, inert, sterile and safe
- Completely free from disease and viruses
- No known toxic effects on plants or humans
- Can be mixed with Vermiculite
- Can be added to soil when planting trees & shrubs
- Neutral pH value
- Will not decompose
