What Time of Year Do Geraniums Bloom?

Geraniums (Pelargonium spp.), also known as common or zonal geraniums, are cozy home or garden plants, with clusters of showy blooms in various colors. Their leaves add interest; some are round and have patterns that include red, orange or yellow shades. Outdoors, geraniums thrive in U.S. Department of Agriculture plant hardiness zones 8 through 10. Because they require lots of sunlight and cool night temperatures to flower, seasonal weather is key to blooming.

Temperature Requirements

Geraniums require cool nighttime temperatures between 50 and 60 F to induce blooming. This means that spring, early summer and autumn are the main blooming times, but the exact season depends on the climate and the type of geranium you're growing. For instance, the Martha Washington geranium (Pelargonium domesticum), or regal geranium, flowers in spring, with a few straggling blossoms in summer.

Light Requirements

Geraniums require a full day of sunlight to bloom, which rules out flowering in winter unless you supplement natural light for a few hours a day. Low sunlight reduces geraniums' ability to photosynthesize, which means they can't store as much energy as they can when they receive an abundance of light. Whether you're growing them outdoors or indoors, place them in full sun; they survive in hotter locations than many other foliage plants.

Overwintering Potted Geraniums

Protecting geraniums from winter frost is key to their survival and future flowering. They go dormant in winter and can survive without soil during this period. Dig up the plants, gently shaking the roots free of the dirt, and place them in paper bags to store them in a cool, dark spot for the winter months. Submerge the roots in water for an hour or two every few weeks, or two to three times before spring. You can remove dead stems and repot your geraniums in late March or early April. Set them in a sunny spot to transition them from dormancy to the growing period, and enjoy their fresh flowers in the summer.

True Geraniums

True geraniums belong in the Geranium genus and thrive outdoors in USDA zones 3 through 8. Their needs differ from common geraniums' needs, with some preferring partial shade to full sun; they also tolerate colder temperatures. However, their flowering periods are similar to those of common geraniums. Depending on the variety, they blossom for weeks or months in spring, summer or fall.


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