hey all

I have a lot of california wonder pepper plants and the first has just started producing fruit. The first fruit has developed a black bruise like blemmish that looks like its spreading. Does anyone know what is the cause? And how to prevent it.
We are just at the beginning of summer. Plants are in containers in my greenhouse. I have toms etc in greenhouse its just perfect temp in there for them at this time of year. The greenhouse is very well ventilated and never gets too hot. When real summer comes i will move them outside. I let them dry right out before i water again but not to wilting stage. I fertiluze weekly with a tomato fertilizer? Is that ok?
The temp in greenhouse ranges from 13 at night to high twenties through day (celsius). Plants are very healthy and thriving apart from said problem.
I have never had much luck with pepper so determined this year was going to be a good crop.

Thanks in advance

Dan