Geraniums flower from spring until fall whether grown in pots or garden beds. Each geranium produces clusters of flowers with color options including red, white, pink, orange and lavender. The flowers remain in bloom for most of summer as long as the geraniums receive the proper care.
Geraniums don’t tolerate frost. Whether you grow in outdoor pots or in beds, place the geraniums outside only after all frost danger passes in spring. It’s better to set the plants out later than to chance frost damage. Protecting plants already outside in the event of late frost helps save the geraniums. Covering bedding plants with a paper bag prevents damage from light frosts.
Geraniums flower best in full sun and perform poorly in shade. Soils rich in organic matter and nutrients provide the best growing medium for the geranium. Working compost into flower beds prior to planting helps add organic matter to the soil. Regular fertilization of both garden and potted plants throughout the summer helps replenish the nutrients the plants need. Applying a balanced slow-release fertilizer at planting provides the necessary nutrients for the entire growing season in garden beds. Pots need a soluble fertilizer application every two weeks.
While geraniums won’t thrive in dry soils, they also can’t tolerate wet, soggy soil. Once weekly watering where the top 8 inches of soil is thoroughly moistened provides sufficient moisture for most bedding plants. Potted plants may require more frequent watering as they must be watered once the top 1 to 2 inches of soil dries out in the pot. A mulch helps retain soil moisture so the plants require less water.
Deadheading, or the removal of wilted flowers, encourages geraniums to produce more flower buds. Once flowers wilt they begin forming seeds which takes energy away from flower bud formation. Cutting off the flower heads as they fade stops seed formation and diverts the energy back into bud formation.
While technically perennials, geraniums are often grown as annuals since the first fall frost kills the plant. Overwintering potted geraniums in a sunny indoor window allows you to keep the plants alive as perennials. Other overwintering options include potting up bedding plants or overwintering bareroot plants. Bareroot saving consists of digging up the plants and hanging them upside down in a 45 to 50 degree Fahrenheit room during winter, taking them down once monthly to soak the roots so they don’t dry completely. Geraniums also root readily from fall cuttings, which allows you to start new plants from your old ones each winter.