While shopping for zonal geraniums at the larger plant centers you may be confused when confronted by the plethora of plants they call "geraniums." Horticulturists with Washington State University suggest that you look at the foliage. If it has a dark area circling the middle of each leaf, it’s a zonal geranium. From there, it’s just a matter of choosing from among hundreds of species that bloom in white, red, shades of orange and shades of pink. Zonal geraniums are hardy to U.S. Department of Agriculture Hardiness Zones 8 through 10.
Raise your zonal geranium in full sun in the northern part of the U.S. Gardeners in warmer regions should provide afternoon shade for the geranium.
Keep the soil moist at all times during the summer. When the weather cools, allow the soil to dry out almost completely before watering.
Fertilize pot-grown zonal geraniums weekly during the growing season with 20-20-20 fertilizer. Ground-grown plants can be fertilized every other week.
Pinch 1 inch from the tips of new shoots if you want the zonal geranium to produce more growth. Pinching sets back flowering for one month, cautions horticulturists with Washington State University.
Overwinter the geraniums by digging them up, cutting the stems to the crown and hanging them upside down in a cool, dry area. Replant them in the garden in the spring when all danger of frost has passed.