Flowering occurs approximately 12 to 16 weeks after sowing. Suggested seed-grown geraniums for Iowa include varieties in the Orbit and Sprinter series. A series is a group of closely related varieties with uniform characteristics, such as height, spread, and flowering habit. Generally, the only characteristic that varies within a series is flower color. A commercially prepared medium, such as Jiffy Mix, is a good germination medium.
Gardeners can prepare their own medium by mixing equal parts sphagnum peat and vermiculite.
During germination, damping-off of geranium seedlings can be a serious problem and is caused by various types of fungi that attack the seedlings and destroy them. To discourage damping-off, containers used for starting seed should be clean and have adequate drainage. Previously used containers should be washed in soapy water, then disinfected by dipping in a solution containing one part chlorine bleach and nine parts water. Firm the medium lightly, water thoroughly, and allow it to drain for several hours. After sowing, thoroughly water the medium by partially submersing the container in water.