Plagron - Perlite

Puffed volcanic rock to mix through your growing medium. It makes the mix airier, drains excess water away faster, and is completely sterile in itself. Available in two bag sizes.

Perlite mainly changes how often you water

Perlite is nearly always sold on drainage, and that is fair enough. But the consequence you actually notice in the grow room is a different one: a pot with plenty of perlite holds less water, so it dries out sooner. You water more often, in smaller amounts.

That is exactly why no single correct mixing percentage exists. Mix in a little and the pot stays damp for longer, which gives you slack on a day you cannot get to it. Mix in a lot and you get more air at the roots and less risk of waterlogging, but you also have to be there more often. Hand watering and a drip system call for different percentages.

A fifth to a third of the volume is the usual rule of thumb. Start at the low end and watch how fast your pots dry down, because that is the measurement that counts, not the number in the recipe.

What else it is used for

Perlite is inert, sterile and consistent, so it works on its own too. A layer in the bottom of a pot drains quickly. Placed under a propagation tray it creates root space and keeps the air below humid. It also works as a substrate in its own right, as long as you accept that it buffers very little.

Available sizes

Technical Specifications:

• Type: soil improver and substrate additive
• Composition: 100 percent perlite, puffed volcanic rock
• Properties: inert, sterile, free of pathogens
• Use: mixed through soil or coco, as a drainage layer, or as a substrate on its own
• Working with perlite: wet it before mixing and wear a dust mask, because the dry dust is fine and irritates the airways

Frequently asked questions

How much perlite do I mix through my soil?
A fifth to a third of the volume is a common starting point. Then watch how fast your pots dry down and adjust: drying faster than suits you means less perlite.

Do I need to rinse it first?
Wetting it is enough, and you do that mainly against the dust. Perlite gives nothing off into your nutrient solution.

Why a dust mask?
Dry perlite throws off a lot of dust, fine enough to breathe deep. A spray bottle over the bag before you start takes care of most of it.

Can I reuse it?
Yes. It does not break down and it does not change shape. Pick out the old root debris and rinse it through.