Posted: 25/05/2015 at 11:29
Normally for raising seeds I make my own from sieved peat, seed fertiliser (Chempak) and vermiculite. For potting on I don't sieve and add Chempak potting fertiliser, grit and or vermiculite. These work well as you control the mix.
Last year I bought 6 proprierty bags only to find (too late to return) they were breeding bags for black fly and other nasties - these were a pest for some months.
I note that compost manufacturers still use peat as a base. My usage is miniscule compared to these commercial suppliers. But only to 2020.