Perlite and vermiculite - what's that all about?

Something that has bothered me for some time now. When preparing the annuals for the garden, the packet of seeds usually says 'cover with vermiculite and water' - as the final stage of the instructions.

I never do this - because I don't have any vermiculite to hand - I just throw another handful of compost over the top of the seeds and all seems well.

I'm also confused about when to use perlite or vermiculite - I understand what each is - but don't know why one would be preferred to the other and under what circumstances.

Anyone out there able to enlighten me please:

- are the two interchangeable?
- what is each used for?

Thanks all.

 

I use neither when sowing seeds, but I mix both into the compost when re-potting my houseplants (saintpaulias, hoyas, baby streptocarpi). It's to make compost lighter,more breathable, at the same time better retaining water.
Many people would put cuttings in pure perlite to root.
Perlite is made if glass (???) - it's just for aeration and water retention. Vermiculite - mineral based - it has some traces of micro elements needed to plants.
I think it's easier for seeds to pull up though perlite or vermiculite, because some composts may be heavy.

 

Hi,

Think this link give a good description of both and how best to use them.
The Differences Between Vermiculite Vs. Perlite and When to Use Each

As suggested by other members, using a small pot full of water and perlite seems to work very well for rooting cuttings, though have only used it on Fuchsias so far, with a 98% success rate