The rose of Sharon, a member of the Hibiscus genus, can be easily started from seed right in your own home. Use freshly collected seeds, or store your seeds over the winter and start them two to three months before your last frost. To grow rose of Sharon from seed, the biggest key is keeping the soil moist throughout and supplying adequate light. Once your seeds are started, grow your seedlings until they are at least 6 inches tall before they go outside.
Set up your seed tray or pots on a flat surface near a sunny window. If you don't have a good sun spot, set up a grow light to hang about 8 inches above your plants. A clamping desk lamp is fairly inexpensive and can hold grow lights.
Add potting soil or seed starting mix to your pots until the soil is about 1/2 inch from the top. Lay a seed in each pot, or seed tray well, near the center. Cover over the seeds with a quarter of an inch of soil followed by 1/4 inch of sphagnum moss.
Add enough water to the pots to make the soil moist, but not soggy. Often watering from the bottom of the pot, by placing it on a dish or in a bowl can help keep you from over watering. When you see moisture at the top layer, you'll know the entire pot is moist.
Place the cover over your seed tray or slip your pots individually into plastic baggies to create a makeshift greenhouse. Leave the pots and tray alone for the next 2-3 weeks, adding water only when the soil looks dry.
Remove any covering once your seedlings have broken through the soil and are an inch or two tall. Replace them in the sunny window or under the grow light. Do not allow the soil to dry out, however, as the water will evaporate faster now without a covering.