Perlite, pumice

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MartP
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Perlite, pumice

Post by MartP »

I've got a quick question, I don't understand the difference between using perlite and pumice. Can perlite be used instead of pumice in a soil mix? Which properties of the soil are changed when perlite is used instead of pumice?
DaveW
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Re: Perlite, pumice

Post by DaveW »

Main problem is perlite tends to float if you water by dipping the pots, or water into the top of the pots.

"Pumice vs perlite:

Some growers swear by perlite to lighten soils and enhance aeration. For years it was the industry standard. It’s the white bits in potting mixes.

According to Austin Petelski of General Pumice, perlite is inert and inorganic, and is created by heating pumice to the point it pops like popcorn.

My own experience is perlite floats to the surface of pots, and in the garden makes tidal drifts of white after watering. Nothing stands out in a garden more than white. Unlike perlite, pumice stays put and doesn’t call too much attention to itself."

http://debraleebaldwin.com/soil-mix-for ... important/" onclick="window.open(this.href);return false;
MartP
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Re: Perlite, pumice

Post by MartP »

But is there any difference in cactus growth (or general plant growth) if perlite floats to top? Is the drainage still good or would root rot and similiar problems occur? Also, wouldn't it float back down as time goes?
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greenknight
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Re: Perlite, pumice

Post by greenknight »

The perlite that's buried stays put, only the stuff in the surface layer floats around. Doesn't hurt the plants. If you cover the surface with a gravel mulch, that will prevent the problem. Perlite works well enough otherwise, and is available many places you can't easily obtain pumice.
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MartP
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Re: Perlite, pumice

Post by MartP »

Yeah that's why I was asking. Where I am there's a shop that sells perlite, but I'd have to get pumice through sites like e-bay and pay a lot for shipping. Thanks for the answers :)
DaveW
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Re: Perlite, pumice

Post by DaveW »

There is a difference in weight of course, perlite is very light, being puffed up pumice, but I have used both without any problems.
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greenknight
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Re: Perlite, pumice

Post by greenknight »

Yes, you might want to add some gravel for weight to make the pots more stable.
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Steve Johnson
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Re: Perlite, pumice

Post by Steve Johnson »

You can also use gravel as a top dressing (I've been doing this for a lot of years). A good thick layer of it will keep the "floaters" down.
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MartP
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Re: Perlite, pumice

Post by MartP »

Yes, I've noticed that it's very light. I was surprised by it. My mother always said it has the properties of styrofoam...
Thanks for all the help!
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