The Best Annuals for Sunny Window Boxes

Nicotiana

• Native to the Americas, nicotiana (Nicotiana spp.) is a member of the Nightshade family and related to tomatoes, eggplant, potatoes and petunias. Although species varieties grow upwards of two feet tall, newer hybrid varieties grow much shorter. The Domino series of hybrid nicotianas are available in a total of 13 colors, including red, crimson pink, lime green, white and bicolors. They grow just 12 to 18 inches high. The variety Avalon Bright Pink has bright pastel pink flowers and grows just 10 inches high, making it ideal for all containers, especially hanging baskets.

Lobelia

• One of the few true blue annual flowers, lobelia (Lobelia erinus) is a low-growing annual suitable for cascading over the edge of a sunny window box. They grow just six inches high but spread up to 12 inches wide. Blue, and other deeply colored lobelia varieties, have foliage that turns deeply bronzed when grown in full sun. In partial sun, the foliage is greenish-burgundy. The plants have a dense growth habit with finely textured flowers and foliage. Although they prefer moist, cool soil, they adapt well to hotter and drier conditions, according to Ohio State University Extension.

Gazania

• A daisy-like flower, gazania's (Gazania ringens) ray-like petals come in many more colors than daisies, from yellow to orange, red to pink, and even striped, but all with a prominent yellow center disk. Gazania is native to South Africa and is tolerant of hot, dry soil of low fertility. They bloom best during hot weather and may carry the show in a sunny window box during the hottest days of summer. They grow up to 18 inches high and spread from six to 18 inches wide. One of the few varieties that closes its flowers after dark, gazanias produce even more blossoms when the faded flowers are removed regularly.