Cotton is a southern subtropical crop. The plants need at least 160 days of not only frost-free weather but warm weather. Temperatures have to range from 60 degrees at germination to almost 90 degrees at fruiting. Planting the seeds is not difficult, but it is a rather picky plant; too much rain or humidity at the wrong time can mean disaster for the cotton farmer. Home gardeners, however, can control the environment and grow cotton for craft project, flower arrangements or just for fun.
Planting Cotton Indoors
Fill a 4-inch pot with potting soil mixed with a small handful of compost to within ½ inch from the top. Wet the soil and place it in a sunny location to warm up.
Place four cotton seeds 1 inch deep into the soil and firm the soil around the seeds. Keep the pot in a sunny location, turning a quarter-turn every other day.
Add just enough water to dampen the soil when the top inch has become dry. The seeds should sprout in seven to 10 days. Once you have leaves, water once a week to keep the roots moist.
Transplant or discard the three weakest plants that emerge and increase the size of the pot to a 12-inch pot when the plant fills the 4-inch pot.
Planting Cotton Outdoors
Choose a location that has full sun and drains well. Remove all grass and weeds from the location for planting.
Place a 1-inch layer of compost over the soil bed and till it into the soil. Water the bed and allow it to grow out any weed or grass seeds that may still be in it. Pull all weeds as they emerge.
Using a soil thermometer, take the temperature to ensure the soil is warm enough for the seed. It must be 60 degrees, 6 inches deep for three days in a row, after all threat of frost is gone.
Use a hoe to make rows in the bed. Rows should be 2½ feet apart and the seeds will be planted 4 inches apart. Drag the hoe to create the planting furrows an inch deep.
Water the soil to completely soak it once the temperature is right. Check to make sure the soil is wet a few inches deep.
Plant a group of three seeds in each location in the moist soil, 4 inches apart. Firm up the soil around the seeds and place an inch of loose soil over the seeds. The seeds should sprout in about two weeks with no additional watering.
Start watering again, once or twice a week depending on the weather, one month after sprouting. Stop watering 16 to 18 weeks after the planting date to allow the bolls to dry out and open.