Geraniums fail to flower when they have inadequate fertilizer, light or water. Geraniums grown in containers also need large enough pots to support spreading roots and deep watering.
Geraniums should be fertilized with a 10-20-10 compound at the beginning of the growing season and then again every four to six weeks, according to the Clemson University Cooperative Extension. The plants need a daily minimum of four hours of direct sunlight, although partial shade in the middle or late afternoon is beneficial in the hottest climates. Geraniums also need thorough watering and good drainage to bloom. Wilting is a signal that a plant needs more water.