What causes ordinarily green-to-red peppers, such as jalapenos and cayennes, to turn a dark purple sometimes? Is it too much, or too little fertilizer, or something else?

Well, there is a possiblity that there is a genetic misprint in that fruit.

For example, there are many genetic strings about appearance, color, etc. There could have been a mutation in that specific fruit or a throw-back stray genetic marker alter the color.

I haven't found any information yet on the Cayenne Pepper but still looking.

What I did find on the jalapeno though, was an article from CNN. Here, Paul Bosland, a university chili breeder and director of the school's Chile Pepper Institute, was talking on peppers. The only comments he had to say were this.

"This purple trait, we have to get rid of that," he said. "People want certain kinds of chilies. People just don't buy a jalapeno that's purple. You want it green and that's just the way it is."

Another guy reported there was no bad taste or anything. He just turned his into Chipoltes.

I could not find anything that said they were bad if they were purple.

I'll keep looking though.

I did just find this. They actually do make a purple jalapeno.

Purple Jalapeno- Somewhat larger than other jalapenos, but with the same thick walls and heat. Fruit turns dark purple and stays that way for a long time before finally turning red. Very attractive in salsas and other dishes, especially when combined with a mixture of other jalapeno colors. 75 days.

Goodearth garden center

[This message was edited by esencia on 08-20-03 at 02:05 PM.]

Peppers, including bell, turn purple before ripening. When a pepper is green it is not ripe, thus a harsh, stronger flavor. It is ripe once it turns to either red or yellow, (color depends on the variety).
Have you ever noticed young bell pepper plants at the nursery marked as sweet peppers? They won't be "sweet" until they've turned color. This may be the reason the reds and yellows are more expensive at the grocery. More time and tending on the bush.