What's so good about Perlite/Vermiculite?

I've heard a lot of talk about perlite and vermiculite, but what's so good about it? I've just googled it and all I found was articles written by companies that are trying to sell me it, and not much from horticulture and gardening folks.

What exactly are the benefits of using it?

 

Hi Clueless1. From what I know of it, it's a basic means to reducing the amount of compost you use in potting/repotting seedlings, plant material etc. It also helps to reduce the weight or pressure against delicate cuttings. Personally, I believe that you're right, those who sell it want to make money from it. I haven't used it, but then I prefer to do things the old fashioned way... as cheaply as possible.

 

I have used vermiculite quite a lot for propagation and find it very useful. It really helps with the water management of compost - holds quite a lot of water within each particle but drains freely between the particles ( hope that makes sense!)
I find that delicate seedlings and cuttings transplant much better from compost including vermiculite - you can see a much large root system and each root cap is protected within a granule of vermiculite.
I also find it very useful for covering seeds - contrasting colour to compost so you can get it more even. Seeds seem to do well in it - reminds me we always get masses of self-sown seedlings in the gravel but rarely in the borders!
It's also 100% sterile and a bag goes a very long way
Only down side I can see is that it takes a lot of energy to produce

 

I sow seeds on the surface of John Innes Seed Compost (or just lightly push into the compost for "slightly larger seeds" - I don't mean Beans!) and then sprinkle vermiculite over the top.

I have a small bag that has lasted me 2 seasons already, and is only half empty.

I mix perlite with potting compost when I want a more open, free draining, compost. I quite often find perlite in pots of plants bought at the nursery.

Neither are very green though (mined and associated with asbestos injuries in the past, IIRC)

 

Wow! I didnt know that! Lets not use it then! I never did luckily!
I wanna do gardening as green as possible!

 

I reckon I am as green as a green thing, but there is lots that I do that isn't green ... do you drive a car? take a bus? train? fly on a plane? heat your house with Oil, Gas or Electricity? Gotta get these things into perspective but even so, I ain't very green, over all, I reckon :(

Here's what wikipedia says:

http://en.wikipedia.org/wiki/Perlite
http://en.wikipedia.org/wiki/Vermiculite

 

I always mix vermiculite in with the compost when I'm potting up or sowing seeds in trays or pots. It seems to stimulate root growth and, for establshed plants in pots, it reduces the risk of water logging.

Try some!

 

Thanks all. I've already bought a small bag of the stuff, which I intended to use for trying to increase my success with cuttings. The reason I suddenly took more of an interest is because I was reading about 'square foot gardening' (a technique that Kristen kindly put me onto). The guy that promotes it says to use one third vermiculite in his compost formula, but I figured that while a little bag is ok for cuttings, I didn't want to spend a lot of money on getting loads of the stuff unless it was pretty amazing.

Incidentally, when I was on holiday in Lanzagrotty one time, we learned that they use the volcanic rock that is naturally abundant on the island as a sort of mulch for the flower beds, as it captures dew through the night, and helps keep the ground moist. Something that is quite important for them given that they have hardly any rainfall. I guess its the same sort of thing in a way.

 

" I didn't want to spend a lot of money on getting loads of the stuff unless it was pretty amazing."

I think you can get it in building supplies stores (or perhaps Perlite, I forget) - some sort of insulating material I think. If that is OK for garden use I expect it will be a cheaper way of buying it in bulk than at the Garden Centre

 

That's not a bad idea, but I googled about and one online garden supplies place sells 100L sacks for £20. I reckon that would be plenty for the size of my garden.

http://www.gardendirect.co.uk/perlite-standard-grade-p-490?zenid=9fvqlsjkqe8k57ot0paqot8nl7

 

I use fine and medium vermiculite at work for covering seeds, nothing else.
It gives a more sterile environment for seeds to germinate in as Pithium and other (damping off) fungii don't spread so readily on it.

 

That's useful to know, thanks. When I've raised stuff from seed I usually find various fungi growing on the surface of the soil (mini toadstools - probably because I can't get the moisture level just right). I might start using vermiculite in the way you suggest.