These visual clues can help you spot the ones that pack some heat. Jalapenos are no different, and a few visual clues can give you a good idea of how hot your pepper is going to be. Look for a darker green colorSmitt/Getty ImagesMost grocery store jalapenos are green, but not all are the same shade. They’re a natural characteristic known as corking, and many pepper growers consider them the best visual indicator of a spicy pepper. Although researchers haven’t definitively proven that corking predicts a hotter pepper, many growers still consider it one of the best visual clues to look for.