While people often start geraniums from seedlings or transplant fully grown plants, more people are learning how to grow geraniums from seed, in order to take advantage of the many hardy hybrid varieties that are now available.
Starting the Seeds
Plan to start your geranium seeds in January, as they take a long time to get started. To have plants ready to flower in the spring, start your geraniums in mid- to late-January, as seeds will flower approximately 12 to 16 weeks following sowing.
Choosing Your Supplies
Most commercial potting mixes are fine for starting and growing geraniums. If this is not available, add sphagnum moss or compost to the soil found in your garden. It’s important that whatever type of container you choose to start your seeds in has adequate drainage to prevent damping off and problems with fungi, two common and serious conditions that can destroy your plants. If you are planning to reuse containers, be sure to clean them well with soapy water and disinfectant.
Planting the Seeds
Fill your container with soil to about 1/2 or 1 inch from the top. Water the potting medium well and allow it to drain. Plant the seeds about 2 to 3 inches apart, in rows, and lightly cover with a very small amount of soil, about 1/8 inch. Water thoroughly and allow it to drain once more. Cover the container with plastic wrap.
Growing the Seeds
Keep the container out of direct sunlight, but where bright light is still available for much of the day. The ideal temperature for germination is 75 F. Depending on conditions, the seeds may germinate within five days or up to two weeks. Once germination has occurred, remove the plastic wrap. Once the first true leaves have unfolded, seedlings can be transplanted into individual containers.