Everything You Ever Wanted to Know About Perlite (A Guide for Hydroponics and Soil Growing)

Perlite is a versatile growing medium that can be used both in soil cultivation and in hydroponics. This material stands out for its lightness and porosity and is suitable as an additive to horticultural substrates or as a standalone growing medium in hydroponic systems. In our guide, you will learn how to use perlite in the garden as well as for indoor and hydroponic growing.

Perlite is a naturally occurring volcanic glass that expands to several times its original volume when heated to a temperature of approximately 850-900 °C. The result is a light, porous material resembling crushed popcorn. Perlite is widely used in various fields, especially in plant cultivation, but also in construction, industrial filters and as a carrier for chemicals. Perlite is chemically inert (inactive), sterile, non-toxic and very stable.

Advantages of perlite in soil cultivation

Soil aeration: Perlite is porous and creates air pockets in the soil, allowing roots better access to oxygen. The root system is therefore more abundant, more resilient and healthier, which is reflected in the vitality of the plants.

Better drainage: When mixed into soil, perlite affects its retention properties. The substrate drains better and retains less water, which helps prevent overwatering. This is especially beneficial when growing species prone to root rot.

Preventing soil compaction: When growing in pots or raised beds, the soil becomes compacted over time. Lightened horticultural substrates with perlite retain their retention properties for longer and the soil remains loose for a long time.

How to use perlite in soil cultivation

For aerating soil in outdoor beds: When establishing a new bed or planting, mix perlite with soil, peat or horticultural substrate in a 1:1 ratio.

For growing in pots: Mix horticultural substrate with perlite in a 3:1 ratio. The resulting mixture will have better drainage than the original unlightened substrate.

Germination: Perlite is an excellent medium for seed germination because it retains moisture without becoming waterlogged. You can create a germination and seedling pre-growing mix by combining perlite and peat in a 1:1 ratio. Do not forget that neither perlite nor peat contains available nutrients, and young seedlings will need to be transplanted or fertilised soon.

Perlite in hydroponics

Hydroponics is a method of growing plants without soil, based on nutrient-rich water (nutrient solution) and an inert growing medium. This can be mineral wool, expanded clay, coconut substrate or perlite. Perlite does not retain water and is suitable only for certain types of hydroponic systems, namely drip irrigation, DWC, NFT, wick methods and Dutch bucket or the AutoPot system. As a medium, perlite is not suitable for flood trays or for hand watering or other methods.

Hydroponic systems using perlite as a growing medium

• AutoPot – Unique self-watering systems for indoor and outdoor use that do not require connection to electricity. The ideal substrate for use with an AutoPot pot is a 50% mixture of perlite with soil or coco.
• Atami Wilma – Popular hydroponic systems of various sizes with drip irrigation for indoor growing.
• Terra Aquatica – A top-tier hydroponic system, the spiritual child of hydroponics pioneer Wiliam Texier. The range includes various types of hydroponic systems suitable for indoor and outdoor use, propagation trays and fertilisers.

Perlite has neutral pH and does not react with the nutrient solution in hydroponic systems. Nevertheless, it needs to be replaced regularly, because algae can settle in the pores, which will show as a green colour on the surface. When using perlite in irrigation systems, take care with small particles and dust, which can clog filters and drippers.

Would you like to learn more about hydroponics and indoor growing? Visit our Higarden blog, where we will introduce you to news from the world of growing and useful advice for growers.