Cotton (Gossypium spp.) is grown for the fibers it produces, which are made into clothing as well as medical and industrial supplies. Cottonseed oil is made from the seed and the hulls are used for animal feed. However, the gardener can grow cotton simply for the enjoyment and educational experience of watching the cotton form on the plant. Cotton takes 150 to 180 days from planting to produce cotton. Cotton is a warm-weather crop, so soil temperatures must be at least 65 degrees 4 inches deep for three consecutive days before planting. Checking the soil temperature can be done with a soil thermometer.
Locate an area of the garden where the sun shines for six or more hours each day for planting cotton seed.
Soak the area with water every day for three or four days to establish a deep level of soil moisture. A deep level of moisture is important for cotton because of the rapidly developing deep root system. The taproot of a cotton plant may be 10 inches deep before the seedlings emerge. That is why warm soil temperature and deep moisture are important when growing cotton.
Clear the area of all weeds and loosen the soil to a depth of at least 2 inches. Spread a 1-inch layer of compost over the planting area and gently work the compost into the top 2 inches of soil. Rake the area smooth.
Plant seeds 1 inch deep and 4 inches apart. Don't pack soil over the seeds; just lightly firm the soil. The soil should be slightly damp from previous water applications. You do not need to do anything else until the sprouts emerge in about 15 days unless the seeds are planted in hard sun-baked crusty soil. Then you should keep the soil surface damp, but not wet, until germination, so seedlings can make their way through the hard soil surface.
After sprouts emerge, no extra moisture is necessary because the plant is living off the deep moisture provided before planting. After four or five weeks, water once a week by deep soaking the plants every seven to ten days. Cease watering when the blooms fall off the plants and cotton bolls or pods begin to form. After that time, the plants will begin to dry and the leaves will fall off. The cotton balls or pods will eventually split open and the cotton will be clearly visible. When you see the full ball of cotton and the pod has fallen away, the cotton is ready for harvest.