[Eightball]

Are any of these things worth adding to my seed starting mix? Been reading a bit about them but just wanted to know peoples opinions/personal experience.

[Totty]

I use vermiculite (fine grade) in more or less all compost mixes. It helps retain water as well as keeping the mix light and airy. Coir, waste of time for veg in my opinion.

Totty

[Trillium]

I use perlite because it's more available to me. I could use vermiculite if I could find it. Coir is useless. Hate the stuff.  As said, it helps loosen potting mix. Most mixes include it but to varying degrees.

[shoozie]

I use vermiculite too - I sieve it when mixing a seed compost and for some seeds that prefer a little light rather than a compost covering. 

[Hampshire Hog]

I use vermiculite for seed sowing in pots and trays
I just sprinkle it on top of small seeds to help them germinate without having to push up through heavy soil

Cheers HH

[GreyScales]

Where does everyone get their vermiculite by the way? I had trouble getting a suitable quantity last year.

[Goosegirl]

Vermiculite retains water whereas Perlite doesn't so provides better drainage and aeration. so bear that in mind when choosing.

[Eightball]

ebay or amazon sell it.

[mumofstig]

Vermiculite retains water whereas Perlite doesn't so provides better drainage and aeration. so bear that in mind when choosing.

I don't think that's right Goosegirl 

Perlite is white in color, very light weight, and has high water holding capacity and high aeration properties (Figure .

http://edis.ifas.ufl.edu/hs169

[Goosegirl]

Oooh - only just read that somewhere very recently. Having just looked again via Giggle, it seems that perlite can retain water, but by no means as much as vermiculite.