Rieger begonia (Begonia x hiemalis), also known as winter begonia, is a cross between wax and tuberous begonias. Attractive little houseplants, Rieger begonias have red stems and small, rose-like blooms. Although begonias can be grown outdoors in the garden bed, Rieger begonias do best indoors, as a houseplant.
Place the Rieger begonia in an area of the home where the temperature remains at 70 degrees F during the day and between 60 to 65 degrees F at night.
Give the Rieger begonia bright light, but do not place it in direct sun. An east-facing window is ideal.
Fertilize the begonia with a 15-30-15 formula, diluted to half the strength recommended on the label, every two weeks while it is blooming.
Water when the top inch of soil becomes dry. Drench the soil until the water runs out of the bottom of the pot. Avoid getting water on the leaves.
Remove dead flowers to encourage the begonia to produce new blooms.
Cut the Rieger begonia back to 3 inches above the soil when it begins to go dormant (when it has finished blooming). Place the pot in a shady area (not dark) that remains between 60 and 65 degrees F. Allow the soil to dry almost completely before watering.
Transplant the Rieger begonia when you begin to see new growth. Use a container that is one size larger than the current pot and fill it with African violet soil mix. Begin watering and fertilizing as you did prior to dormancy.