I generally try to get my main sowing compost in December, 6 bags of last years New Horizons will be on special offer at Wyevale, guarantee it... When I'm sowing I put a layer of that in the pot, sow the seeds and top with a proper John Innis Seed compost, generally get great germination even though my watering regime can be a bit erratic,,,, for most of the potting on I use a mixture oflast years greenhouse soil (save half a dumpy bag when I dig it out) mixed with council compost and a bit of BFB. We can buy the compost straight from the recycling yard, half a ton will be about 15 quid ... any left gets used as a soil improver on the plot