Red Rubin Moon Hens & Chicks - Sempervivum - Very Hardy - 4" Pot - Moon Charms The more sun and heat, the darker the color Hardy Zones 4-9 Mature Height: 10-20" Full Sun Sunlight brings out bright colors in Sempervivums. When planted in shade or grown indoors away from a sunny window, many varieties tend to fade to a plain green color. It can take up to 3 years to develop the pictured colors.