Due to their cold sensitivity, begonias must be grown as annuals in the garden if not lifted or stored. Begonia tubers can be easily lifted each fall and can continue to grow the following spring for over 10 years. They produce abundant flowers in a wide array of colors. Numerous varieties have outstanding foliage, and a few offer trailing habits for basket planting. A relatively tough plant, the begonia suffers from no real diseases and few pests.
Choose a planting location that offers shade for the begonia. Well-draining soil is ideal, with abundant organic matter. Add peat moss, aged manure or bark chips at the time of planting so the soil feels crumbly to the touch. The begonia will not tolerate wet roots for an extended time period so avoid areas with standing water or locations that are prone to flooding during a rainstorm.
Depth and Distance
Plant tubers in the spring after all danger of frost has passed. Cover tubers with a layer of soil that does not exceed 2 inches in depth. The indention in the disk-shaped tubers surface must face upwards when planted. Space the tubers 12 inches apart. Pat the soil firmly over the surface of the tubers.
Watering and Fertilizing
Keep the begonias moist but not water-logged. They will not tolerate drought and will easily perish if the soil is allowed to dry out. Once the begonia tuber has sprouted, apply 2 to 3 inches of mulch around the plant's base. Use peat moss or bark chips. The mulch will help the soil retain moisture, shade the begonia's root system and limit weed growth. Fertilize begonias every two weeks using a water-soluble balanced fertilizer. Follow the directions on the label for application.
Clip or remove dead blossoms. Do not clip the foliage once flowering has ceased. The begonia needs its foliage for storing nutrients to survive the winter months. In the fall the leaves and stalks will begin turn yellow and wilt. Clip and remove them in preparation for storing the tubers for winter.
Dig up the begonia tubers before the first frost. Gently lift the tuber and wash the dirt away. Do not remove the roots from the tubers. Dry them completely for a few days, then dust the tubers using a general purpose fungicide designed for bulbs and tubers. Place the tubers in a box of peat moss and store in a cool, dark place until spring. The location should be low in humidity and maintain a temperature of around 50 degrees F.
Popogate begonias from cuttings or seeds. Use the stem of the begonia to take a cutting. The plant's tubers are difficult to divide and can easily rot. Tuber division must take place when the plant is actively growing.