Bell peppers essentailly come in three ripe colors. Red, Orange and Yellow. It is determined by genetics. There are several green when ripe cultivars out there but they are more rare then green when ripe tomatoes. Bells are used primarily as immature peppers, green, purple, white, etc but ripe bells are rapidly gaining popularity.

Farmerdilla,

Don't mean to be contrary, and I agree with the basic statement that genetics determines the ultimate color of a ripe pepper.

However, last summer, I learned something I didn't until then. I bought some peppers plants labeled simply "Yellow Bell" on a kinda generic label at a chain store garden center last spring.

They grew nice, big, blocky, sort of chartreuse-green peppers. I left some to ripen, and they turned a nice, bright, uniform yellow all over. I figured they were done, but they weren't. The ones left then turned bright orange, and eventually all the way to red.

I wouldn't have guessed that one variety would go through all three color phases -- it thought it was green turns yellow, green turns orange, or green turns red, and that was it.

True some do that. Green to reds are very straight forward, but some of the others do have intermediates like hot peppers.