Imagine flocks of colorful butterflies and hummingbirds visiting your garden all summer long! That’s what you’ll get when you add pentas to your garden plan. Pentas develop sparkling star-shaped flowers all summer long in bold hues of red, white, lavender, purple, or pink. Pentas is a sun lover that grows 18 to 36 inches tall. In most parts of the country, pentas is considered an annual, but in very warm regions, pentas is perennial in nature. Pentas is relatively deer resistant. Hardy from zones 10-11, but frequently grown as an annual in cold-winter areas.. Mature Size: 12-16″ x 12-14″. Full Sun (6+ Hours).