Yes, sow some more. The cut-off point is probably June for sowing these. I have found that late sown ones catch up anyway and, with the terrible spring we are having, you wouldn't have been able to plant them out before June anyway.

Steve, I have had the same problem, especially the yellow courgettes. I put mine in about two or three weeks ago and they have just died back.

Jenny how strange it’s the yellow courgettes that I have had the same problem with.

I grow the spherical ones of both courgettes and cucs Steve and have them in a cold greenhouse. They are looking pretty sickly this year so I'll probably start again if the current cold spell ever finishes.

Sound like your compost is too wet!

You still have time to sow them, sow the seeds on their sides?