Serrano Pepper Seeds (Hot Type). This smaller Mexican hot pepper is spicer than Jalapeno making it great for hot salsa or for eating raw. Peppers average 7.5 cm (3″) in length and 1.25 cm (1/2″) in width. Colours range from red to yellow to brown at maturity. They are delicious when pickled or dried. Scoville Heat Unit Rating – 23,000.