Perlite

Also known as: Expanded volcanic glass

Properties

pH effect	neutral / inert
Water retention	very low
Drainage	excellent
Oxygen to roots	very high
Bacterial surface area	low
Reusability	low (1-2 cycles)
Cost tier	low
Weight	very light

How it affects the system

Almost always used in a mix, not pure: pure perlite holds no water and dries out too fast for most crops
pH neutral and inert; does not buffer or affect water chemistry
Smooth glass surface: poor bacterial colonization compared to porous media
Compacts and degrades over time, eventually creates fines that clog drip emitters

System compatibility

Works well in:

drip
dutch bucket
wicking bed

Avoid in:

NFT channels
deep water culture (rafts)
media bed (ebb and flow)

Care notes

Wet perlite before adding to a system or you will breathe the dust. Wear a mask when handling dry. Standard component in coir-perlite hydroponic mixes; rarely used alone except in some dutch-bucket setups for fast-draining crops like strawberries.

Crops that work in perlite

87 edible crops in the catalog list this medium as compatible.

Sources

Data drawn from: cornell-cea, horticultural-perlite-institute. Last verified 2026-05-13.

Back to growing media reference