The yellow flowering begonia blooms from early summer until the first frost. Found in Africa, Asia and America, yellow flowering begonia species are extremely rare, and some are considered endangered. Most yellow flowering begonias are grown indoors or in greenhouses because they require regular feeding, watering and care of the blooms. You can grow these begonias indoors or outdoors, as long as you have a spot to plant the begonias that is protected yet still receives enough sunlight.
Locate your yellow flowering begonias in partial shade that receives bright, indirect morning sunlight. Find a spot that is protected from wind, hot afternoon sunlight and extreme heat or cold.
Plant your yellow flowering begonias in moist, humus-rich soil. Soften and break up the soil well before planting, using a pitchfork or a rototiller. Work in some organic compost to enrich the soil.
Keep the soil moist by watering once or twice a week to supplement rainfall. Don't allow the soil to dry out.
Feed your yellow flowering begonias an all-purpose, well-balanced flower fertilizer once a month if kept indoors or three times during the growing season if planted outdoors. Follow the dosage instructions on the package.
Pinch off the spent flowers to encourage re-blooming. You also can remove the male flowers that grow on either side of the larger female flower to encourage the female bloom to reach its full size.
Reduce the frequency of watering and fertilizer applications as winter approaches. You want the leaves to dry out and fall off instead of rotting.
If your area experiences hard frosts during the winter, dig up and remove the tubers after the leaves have dried and died off. Store the tubers in slightly moist sawdust or shredded newspaper until spring.
Keep an eye out for fungal diseases that can harm your begonias. If your begonia stems turn soft and rotten and the plant develops a covering of mildew, your begonias most likely have a soft rot disease, botrytis or other fungal disease. Keep the leaves and stems as dry as possible, and treat the begonias with a fungicide, following the directions on the label exactly.