Pentas lanceolata - 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.