Geraniums bloom profusely from early summer until the first hard frost. The plants overwinter well in an indoor, frost-free environment. The proper time to bring geraniums outdoors again depends on your location.
Geraniums perform well outdoors as soon as the danger of frost passes. The National Climactic Data Center provides this information online (see Resources).
Geraniums prefer daytime temperatures between 70 and 85 degrees Fahrenheit. Optimal temperatures at night range from 60 to 65 degree F.
Time of Year
Geraniums grow best when they’re moved outside in the spring in locations with hard freezes during winter. In hot areas, such as southern Florida, geraniums do better if they’re planted in the fall. This provides a long blooming period before excessive heat and humidity stress the plant