When to Plant Geranium Seeds?

Geraniums flower throughout summer.

Several varieties of geranium grow well from seeds, including the Orbit and Multibloom cultivars. Seeds must be sown at the correct time, otherwise the geraniums won't flower until late in the summer. Starting the seeds too early is also a concern, as plants grown too long indoors become weak and leggy.

Indoor Seeding

Geranium seeds germinate and grow slowly so indoor seeding is necessary to ensure the young plants reach maturity. It takes three to four months for a geranium to reach maturity and begin flowering. Geraniums aren't frost-tolerant, so they cannot be placed in the garden until after all spring frost danger is past. Start the seeds 12 to 16 weeks before the last expected frost. For example, if the last frost date in your area is May 15, start the geranium seeds indoors by January 15.

Seed Starting Supplies

Using the right supplies is vital, since geraniums spend so many weeks growing indoors. Sow the seeds in individual seedling pots that are approximately 3 inches in diameter. Use a sterilized, soilless potting mixture to prevent disease problems. These mixtures contain peat, vermiculite, perlite and other nonsoil components. The seedlings need supplemental fertilizer once they are 2 weeks old, as soilless mixes are generally low on nutrients. A general-purpose, soluble fertilizer supplies the geranium's nutrient needs.

Special Considerations

Warmth and light are special concerns since geraniums are sown during some of the coldest days of winter, when the days are still short. Keep the seedlings in a warm room, with a temperature between 70 and 75 degrees Fahrenheit. If your home is cooler, use a seedling germination mat to keep the soil temperature in the optimum range. Fluorescent grow lights also help your geraniums grow well. Set the light fixture 6 inches above the seedlings and leave it on for 12 to 16 hours a day.

Transplanting

Transplant the seedlings once spring frost danger is past. Acclimate the geraniums to outdoor conditions for one week prior to transplanting. Set the pots outdoors in an area protected from direct sunlight and wind. Gradually move them out into the sun so they experience more exposure over the course of the week. After seven days, transplant the geraniums to a full-sun garden bed.

References

• Iowa State University Extension; Growing Geraniums from Seeds; Richard Juaron; January 2008
• University of Nebraska; Growing Geraniums From Seed; Don Janssen; January 2004