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Rock wool vs. vermiculite

Posted by socal_mtngal 8 san diego mtns (My Page) on
Sun, Apr 29, 12 at 3:44

Has anyone tried using stone (or rock) wool in place of vermiculite? I just got a sample and am eager to try it in a small area.

I read that stone wool has been used as building insulation in Europe, but is also being formed in blocks for seed starting and hydroponics. It is made from superheated basalt and chalk, and is touted to be an environmentally friendly, sustainable product.

This stuff is very absorbent, but I have no idea how its structure will hold up in soil over time--it seems to compress with pressure and sort of falls apart if handled when wet. Not sure whether it will be cost effective, either.

Follow-Up Postings:

RE: Rock wool vs. vermiculite

mtngal Unless your rock wool is different than mine, your guess is right on it losing its shape. I tried it and it turned into mush I used it in containers on a lark ,so nothing lost lol.


RE: Rock wool vs. vermiculite


Right! The manufacturer claims that rock wool has the best of both properties: water retention (like peat moss) -and- aeration (like vermiculite). But, if it loses its structure, well... On the other hand, if it breaks down into a material that will compost, it could be useful; but I'd rather it holds up for a little while. I will give it a try in a separate container and report back what happens.


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