The genus Begonia includes more than 1,000 species from tropical and subtropical regions. Most begonias are frost tender, and hardy to U.S. Department of Agriculture plant hardiness zones 10 and 11. However, one species, the hardy begonia (Begonia grandis ssp. evansiana) can grow in USDA zones 6 through 9. While there are several different types of begonias, including semperflorens, Rex-cultorum, rhizomatous, tuberous, cane and shrub-like species, most share similar care and feeding requirements.
Transplant begonias outdoors when the risk of frost has passed. Choose a location where the plants receive filtered sunlight, light shade or morning sun followed by afternoon shade. Typically, eastern or northern exposures are ideal for begonias, which don’t like a lot of sunlight.
Plant begonias in well-drained soil that is rich in organic matter, such as compost or leaf mold.
Space your plants 8 to 12 inches apart to ensure there will be enough room for good air circulation. This helps keep the foliage dry and prevents fungal infections.
Feed your begonias in the spring with a balanced fertilizer, such as 3-1-2 or 2-1-2, diluted to half the strength recommended on the label.
Continue fertilizer applications at half the label-recommended rate every two weeks during the growing season.
Water your begonias only when the soil feels dry to the touch, watering directly to the soil to avoid wetting the foliage. While begonias need moisture, if they are too wet the roots may begin to rot. Too much water can also lead to fungal infections such as powdery mildew. If the lower leaves turn yellow or drop, your begonia is getting too much water.
Bring begonias indoors during the winter months in climates that experience cold winters. Store your plants in a cool, dark place and do not water them.
Leave faded stems on the plant until they drop off, unless they become soft or moldy.