[purplebean]

I think you are being too nice to them, stick them outside and let them get on with it. I did another trough last week and they are all now through. I also think a seed tray is not deep enough, as you don't want to transplant them they need a deeper pot from the start

[Maryann]

Oh right, thanks for that. I did wonder if seed tray too shallow but hubby had already stuck them in it before I knew it.

Never mind - have plenty left to have another go.
Thanks for replies 

[zarazara]

You just plant them in some compost in a pastic tub. plant very thickly,close together. Leave on window sill. When they are about 4 inches or so high,snip off,add to salads or stri fries. Rather like groing mustardandcress.