Posted: 14/05/2014 at 07:42
I'm with scroggin; end of May for me. I'm in the midlands. in my experience if you put them in now they seem to grow much slower than if you put them in when it's a tad warmer. In the past I've been left with little plants that went in earlier than ones that I put in a little later. Also of course, much less risk of frost.