Annual begonia plants are also deer resistant, so keep them in mind for trouble spots in the landscape. Plant wax begonias in a full sun to shaded location. Full sun locations during hot summer days may stress annual begonia plants, making them susceptible to disease. Therefore, in areas where summers are exceptionally hot, plant wax begonias where they will get afternoon shade. Once appropriately placed in the flower bed or hanging basket, deadheading spent blooms and keeping the soil moist is the basis of annual begonia care. Watering correctly is important in the care of begonias. Soil should remain moist, but not too wet. A well-draining soil or potting mix simplifies this task. Water wax begonias at the base to avoid leaf spot and the possibility of fungal diseases.