Have found the same with my Basil and Pepper seedlings in my
greenhouse. I used multi-purpose compost but have subsequently read
that indoor and greenhouse potting should be with a sterilised
compost. I'm sure a bit of algae won't do them too much harm and will
disappear when they are moved outside.


"david" wrote in message ...
I have the same thing with a lot of the compost I have used on the Dahlia
tubers, it's the precursor to Moss, starts like a green algae, then it will
start to grow into moss.
I don't know why it is so predominant this year, same compost I have used
for a few years, and the conditions are the same.