Growing peppers here in North Dakota, we get a lot of black peppers. Our Extension Horticulture Specialist indicated this is a reaction to our cold nights. No problem, just cosmetic. Nels in ND >Many of the peppers go from green to black during the cold months but it >never happens the rest of the year. >The fruits aren't completely black, maybe just a side, or the bottom. The >fruits are not bad either