These are lists of (almost?) everything I’ve tried to grow from seed each year, and whether I’ve had success or not.
How I sow
I don’t really try to conserve seed, since seeds are cheaper than time. If I use the entire packet and have too many plants I’ve lost a few pence, whereas if I carefully use the minimum possible and nothing grows I’ve lost a year. For most perennials I sow entire packets in seed trays, and then put them somewhere warm and light and cross my fingers. Things have been a bit easier in 2016 because this is the first spring with a working greenhouse, so all the seed trays have been out there with an extra little plastic lid on top for extra insulation / heat trapping.