Cotton (Gossypium spp) grows as a perennial shrub but is typically kept as an annual. Winter hardy in USDA Zones 8 to 11, cotton requires a long growing season of 120 to 180 days of completely frost-free weather. Related to the beautiful hibiscus, cotton produces large, showy flowers in mid-summer, making it an attractive indoor container specimen. Cotton plants blossom continually for 3 to 5 weeks, with flowers each lasting about 2 or 3 days. Brown fruit capsules called bolls develop by late August as blooms die off. The fluffy seed pods burst open when they're mature and the cotton is ready for harvest in September.
Fill a 4-inch pot with potting soil to about 2 inches from the rim. Set it in a shallow tray of water until the soil surface feels moist. Remove it from the water and allow it to drain for a couple of hours.
Space 3 or 4 cotton seeds evenly apart on the soil surface. Cover with 1 inch of moist soil, pressing gently to firm into place and eliminate air pockets.
Cover the pot with a plastic food storage bag. Set it in a warm, sunny windowsill. Your cotton seeds will germinate in 4 to 15 days.
Check the soil every day. Do not let it dry out. Water just enough to evenly moisten the top 1 inch of soil, but not enough to make it soggy or wet.
Take the plastic bag off the pot when seeds begin sprouting. Remove all but the sturdiest plant when seedlings are 1 to 2 inches tall. Repot each of them individually to share with friends.
Transplant your cotton seedling when it develops at least 2 sets of true leaves. Move it to a 12-inch pot. Keep the top 1 inch of soil evenly moist.
Feed the cotton plant a tomato fertilizer when it develops 4 sets of true leaves. Fertilize once a week throughout the growing season thereafter. Follow the packaging instructions carefully. Your cotton plant will bloom in 5 to 6 weeks.
Pluck cotton bolls in September when they have split and burst open completely to reveal wads of fluffy white cotton.