Grown as annual bedding plants in much of the U.S., tender perennial begonias require protection from frost. With more than 1,000 species available, begonias grow in a range of size, shape and colors. Attractive foliage varying from deep green to bronze combined with abundant blooms in shades of pink, yellow, orange, red and white creates a striking mass of color to brighten shady nooks. Trim begonias to maintain their size and shape, as they tend to become leggy by midsummer.
Cut back begonias by trimming 3 to 4 inches from terminal ends if the plant becomes overgrown or blooming decreases. Regrowth occurs quickly and a flush of new blooms follows.
Trim stray stems that extend beyond the shape of the plant to maintain the overall shape. Wax begonias, often used a bedding plants or in window boxes, should be maintained in a rounded mound. Use clippers or snap the stems by hand, taking care not to damage existing foliage.
Pinch back the terminal ends of begonias when they are 4 to 6 inches high to force new growth to appear along the stems. Repeat once a week until the plant develops compact foliage. This increases both foliage and blooms.