The plant perform best in big size containers (8inh or more) or plant them on ground
Sunlight: sensitive to temperature changes and to temperatures below about 60 degrees F. (16 C.) You can keep them happy as houseplants or store them dormant over winter
Soil: begonias prefer a light, rich soil. When planting directly in the ground, a moist, well-drained location is optimal and mulch will keep the roots shaded. In pots, make sure to provide drainage holes. A peat-based potting mix is ideal for containers.
Water: Begonia rex should be watered when the soil or pot feels dry, but donâ€™t wait until the plant starts to wilt. You can cut back on water during their dormant period in the winter, watering only when the pot dries out.
Temperature: prefers plenty of indirect sunlight and room temperatures at 65-70 deg
Fertilizer: You can feed your potted plants monthly with any good houseplant food. Too much food will make for a scraggly plant, so pay attention and adjust the feeding to suit your variety. Rex begonias can be temperamental and you just have to find the right conditions and balance for your plant. Donâ€™t feed at all during the winter