Yellow begonia is a tuberous begonia that grows 6 to 12 inches tall as an upright plant and 12 to 18 inches long as a trailing plant. They bloom throughout the summer. These flowers are hardy down to USDA plant hardiness zone 4, which means they survive in areas where the average winter low temperature does not drop below 20 degrees below zero Fahrenheit. This plant is not difficult to grow as long as you know how to create the right environment for it.
Plant yellow begonias in partial shade and well-draining, fertile soil. The plants do best in dappled sunlight or early morning and late afternoon sun.
Water the begonias deeply. Allow the soil to dry slightly before watering again. Yellow begonias are not drought tolerant, so you must make sure they stay moist--especially when in a shaded area or overhang. Do not soak them, however, as this will cause flower drop. Gradually decrease watering frequency in August to prepare for dormancy.
Fertilize the plant monthly during the growing season with a complete fertilizer diluted by half. This kind of begonia needs a good amount of food, but too much will cause flower drop. Stop fertilizing in August.
Pinch off the first few flower buds that appear to give more energy to the plant. Also pinch off the smaller female flowers that flank the large male flowers to promote blooming.
Dig up the tubers of the yellow begonia with a trowel when the foliage turns yellow or after the first frost. Cut the stems to 5 inches and dry them out of the sun. Place them in a bag with peat moss and store in a room between 40 and 50 degrees Fahrenheit. Replant the tubers in the spring.