A greenhouse is a blessing for the gardener whose climate doesn't permit growing flowers outdoors. Not only is a greenhouse the easiest and least expensive way to start seedlings, but there are literally hundreds of different flower varieties that you can plant in this type of indoor atmosphere. Although some flower varieties may have specific instructions (always follow the growing instructions on the package), there is a general way to start most flower seedlings in a greenhouse, starting with soil and environment preparation and planting.
Combine the soil and vermiculite together and fill the containers or starter cups. With your index finger, carefully push two to three flower seeds into the soil, usually about 1/2 inch to 1 inch deep (follow the directions on the seed packet, as this depth will vary). Place the containers in the growing tray if you have a lot of them or different varieties to keep them organized and easy to transport around the greenhouse.
Mist containers lightly with a spray bottle to keep them moist. Continue to do this to keep them consistently wet (not soaked) until the seeds begin to germinate.
Keep the containers under the greenhouse grow lights or in an area of the greenhouse where they will receive full sun for about 8 hours per day. They must be in the sunniest place possible, so artificial lighting for darker areas is suitable as well.
Keep a consistent temperature in the greenhouse of 67 to 70 degrees Fahrenheit. Once the flower seeds germinate, rotate the containers daily so the seeds grow straight up and strong and are not leaning toward an area with brighter light.
Water the growing flowers according to the seed package. When they are young, though, it is usually necessary to keep the soil consistently moist with an irrigation system in the greenhouse or manual watering.
Transplant the seedlings once they are 2 to 3 inches tall. Depending on the size of the fully matured flower, transplant them to a pot that will accommodate the mature growth. Keep the temperature consistent throughout the entire growth stages of the flower, turning them if necessary as you did with the seedlings.
Keep the flowers in the greenhouse with the necessary sunlight and watering until they are fully grown. Then you can either transplant them outdoors or continue to grow them in the greenhouse.