Sunflowers can be grown indoors as well as out, as long as you have the appropriate light source. Growing them indoors will let you enjoy the cheerful blooms for weeks, even if it is not technically the normal growing time. Choose seeds that grow smaller versions of sunflowers because the 10-foot varieties will be too big for plant pots, and they get weak when grown indoors. Choose varieties that are shorter, such as sunny smile, teddy bear and firecracker sunflowers.
Choose a plant pot that has a drainage hole in the bottom. If you only want to grow one or two plants, use a 6-inch diameter container. For more than two plants, use a 12-inch diameter pot. Pots made of clay will let the sunflowers breathe better than those made of plastic in dry environments. The soil will stay more moist in a glazed ceramic pot.
Mix one part compost to three or four parts of an all-purpose potting soil. Put the mixture in the plant pot.
Push the sunflower seeds into the potting soil combination. They should be 1 inch deep. Water the soil well so moisture gets to the seeds. Plant twice as many seeds as you are hoping grow because you will thin out the weaker plants later.
Set up a light above the planting container. Any fluorescent lamp will work; you don't need a growing light. Put the light 6 inches above the plant pot. Once the seed sprouts, you can move the light farther away. It should remain about 1 foot from the top of the plant.
Water the plant regularly so the soil is consistently moist. Use your finger to determine when it needs water. Don't let it become waterlogged.
Give the sunflower eight to 12 hours of direct light daily. Turn the light off at night to give the flower time to rest. Rotate the plant every few days if you notice it leaning in one direction.