Green - all year, Red - late Spring and Fall.
Mexico and the United States.
The green jalapeno is the unripe version of the red which often ships with white veins on the outer skin. This does not affect the flavor or quality. While the the red is a bit sweeter, both have a truly wonderful flavor. Delicious when roasted, stewed or pickled; both are a delight stuffed with cheese or peanut butter and grilled. Heat ranges from hot to very hot.