Pencil-thin cayenne peppers are used fresh in hot sauces and chilis, dried or ground for cayenne pepper or red pepper flakes, as a flavor in oil and vinegar dressing, and strung on a string as an attractive southwestern style decoration called a ristra. Prolific plants produce green, 4″-6″ peppers that turn either red or yellow; very decorative in the garden. 30,000-50,000 Scoville heat units (hot).. Mature Size: 18″ x 18″. Full Sun (6+ Hours).