Tuberous begonias (Begonia tuberhybrida) are known for their outstanding blooms (up to 6 inches across), wide variety of colors and for the fact that they will bloom continuously all summer long if cared for properly. Perfect for shady areas of the garden or in hanging baskets, these showy flowers are native to South America and South Africa and thrive year-round in subtropical and tropical areas. In cooler climates, they are often grown as annuals.
Tuberous begonias are tropical flowers. They can be grown as perennials and left in the ground in USDA hardiness zones 9 through 11. In cooler climates, they should be planted in baskets and moved indoors when fall arrives. Alternately, the tubers can be dug up and placed in a cool, dry location to overwinter.
Tuberous begonias do not like direct sunlight. They prefer morning sun followed by afternoon shade, or a location that is continually in dappled shade. These flowers grow very well in the shaded areas of porches. While some varieties, such as the hardy begonia, are marketed as being able to bloom even in heavy shade, exposure to at least a little sunlight is best.
Soil and Water
Begonias thrive in rich, loamy soil. Heavy watering is necessary for these plants to succeed. Overly wet soil will cause the tubers to rot, however. A careful balance of moist but not too soggy must be maintained. The soil should be slightly wet and crumbly at all times, but not muddy, nor should there be any standing water on the surface. Water the flowers without wetting the leaves, and empty the water-catch tray immediately after the soil has finished draining, if the begonias are in a container.
Begonias are heavy feeders. Fertilize your tuberous begonias with a water-soluble fertilizer at least twice per month during the summer. Choose a fertilizer that is formulated for flowering plants and follow the dosage as per the instructions on the package.
Deadhead (remove wilted blooms) the flowers frequently to encourage continued blooming of the plant. Make sure the begonias have enough air around them, as poor air circulation can lead to the development of fungal diseases such as leaf spot. Begonias should be planted about 9 inches apart, even in containers.