Begonias are a very diverse family of plants. Tuberous begonias grow 12 to 18 inches high with single or double 6-inch flowers, some resembling roses, and come in a variety of colours including white, pink, red, orange, yellow and bicolor. Wax or fibrous begonias grow about 8 inches tall. They have glossy green or bronze leaves and small white, red and pink flowers. Rex begonias have no flowers, but their leaves are big with patterns of colour including bronze, pink, purple, red and green. All grow well outside during the summer.
Plant all varieties in the ground, in window boxes or pots. Trailing tuberous varieties and Rex begonias do well in hanging baskets. Use commercial potting soil in containers and plant one or several in each pot. When planting in the ground, ensure the soil is rich and well-drained. Incorporate 2 inches of compost and peat moss into the soil and till it to an 8- to 10-inch depth. Plant all begonias at the same level they were in the flat. Do not plant any deeper as they are at risk of rotting. Space wax begonias 12 inches apart and tuberous begonias 18 inches apart. Plant Rex begonias in containers as a single plant or plant two if the pot is large enough.
Place pots or plants in a shady area. All begonias require partial shade or their leaves tend to burn. Rex begonias require heavy shade as filtered sun discolours the leaves. Bronze-leaf varieties of wax begonias tolerate filtered sun, but the green leaf types are safer in the shade.
Water all varieties during dry periods when the soil feels dry to the touch. Tuberous begonias need more frequent watering but too much or too little causes the flowers to fall off. Keep evenly moist.
Fertilise tuberous begonias at least once a month using a 10-10-10 fertiliser per package instructions. Those growing in pots benefit from liquid houseplant fertiliser using the package instructions. Wax begonias do not need much fertilisation so feed only once during the summer. Use liquid houseplant fertiliser per package instructions once a month on the Rex begonia.
Remove spent flowers from tuberous begonias by picking them off with your fingers. This keeps the plant looking neat and healthy and promotes more blooms. Wax begonias do not require deadheading because old flowers fall off and more bloom. If the plant becomes leggy, remove tall stems by pinching them back with your fingers. Rex begonias do not produce flowers and need no deadheading.
Dig up begonia tubers after the first frost to save in sawdust over the winter. Wax begonias are an annual and need replanting every year. Bring Rex begonias indoors to grow over the winter and put back out when the temperatures do not go below 12.8 degrees Celsius.
Never cultivate the soil around the roots of any begonia because the roots are shallow and can be damaged.