Every time I talk about seed composts over here in England I always talk about my basic mix as 1 part John Innes compost, 1 part sand and less than 1 part grit. Then compact that in the pot and add a layer of more sandy mix at the top, onto or into which I sow the seed. Then if the pot will go straight outside I tope off with grit.
But then I explain that I then adjust the mix by physical feel, does it scrunch up in the hand too much and so on. And then I talk about basic potting compost as using the same three parts but a full 1 part grit or even more. And I almost never use peat or peat-based composts - but then I don't really grow ericaceous plants so its not much of a problem.
But when I talk to North Americans I have to explain what John Innes compost is - basically a sterilised loam with additions of a standard recipe of additions. There are 4 standard recipes which have more additions of fertilisers from John Innes [JI] Seed, through JI 1 to JI 3.
I want to get an article on such basic things as sowing alpine/rock garden seed for the Quarterly (from someone or some two or three for that matter - feel free to volunteer) so I'm really interested in what you do - garden soil/dirt - sterilised or not - commercial or what.
And from the number of reports about early germination a whole lot of people must be keeping all their pots of seed in the kitchen or playroom or bedroom or wherever.
This year I've sown about 70 pots of seed {surplus seed just ordered} and they are all outside in a frame having been started outside to get covered initially by snow - the cover had ice on it again this morning and the average day temperature is now up to around 4oC and -1oC at night. Usually by now I would have germination but this year I'm so envious of all these great reports.