Geraniums belong to the Geraniaceae family. They are regarded as perennials and annuals, of which many species are indigenous to the Northern Hemisphere. Geraniums can be grown as shrubs, often reaching heights of over 3 feet, or as trailing vines, growing to lengths of 12 to 15 feet. The single or clustered forms of flowers of the geranium come in pinks, white, bi-colors, purple or various shades of red.
If you're reusing planting containers, wash them in hot, soapy water, then sterilize them in a mild bleach and water solution of one part bleach to nine parts water.
Fill up your planting cells or seed starting trays with a good-quality potting mix to approximately 1 inch from the top. Water the container thoroughly, letting the water drain off. Firm the soil by pushing down on it with your hand until it's well packed. Geranium seeds usually have a hard hull. Scratch the surface of the seeds to promote germination.
Place two or three geranium seeds on the surface of the damp soil and space them 1/4 inch apart, in rows that are 1 to 2 inches apart. Cover them with 1/8 inch of soil. Spritz the surface of the seeds.
Cover the trays with a sheet of plastic wrap. Place the seeds where they will receive six to eight hours of filtered light a day, and a temperature of approximately 72 degrees F. Inspect the geranium seeds daily, and keep them moist.
Once seedlings emerge (typically 10 to 21 days), remove the plastic wrap. Water often, and allow the soil to only slightly dry out between waterings. Once the seedlings have a set of leaves, transplant them into larger containers.
Fill up each of your potting plants half full with potting mix. Remove the geranium seedling carefully and place into the pot at just below the set of leaves (about 1/2 inch). Hold the seedling level and straight in the pot, and fill the entire pot up with potting mix. Water each seedling using a steady stream of water.
Put the transplants near a sunny window, and in an area where they will be given an average temperature of 72 degrees. When the seedlings are approximately 4 inches tall, place them outside in a protected area of your garden for a few hours each day for approximately 10 days before migrating them completely outside.