A perennial, cotton grows in tropical and subtropical locations. It does not do well in regions that have prolonged dry or wet spells. Planting occurs in the spring after all danger of frost has passed. The soil temperature must be 15.6 degrees Celsius or higher for cotton seeds to successfully germinate. Harvest of the cotton bolls usually begins approximately 150 to 200 days after planting.
Temperature and Growth
Cotton plants can attain a height of 15 to 20 feet. Under ideal growing conditions, the temperature should hover between 32.2 to 35 degrees Celsius. The plant develops a deep and extensive root system that makes it drought tolerant. The roots can grow as much as 1/2 inch per day, according to the University of Florida IFAS Extension. If the temperature dips below 60 degrees or above 100 degrees, the growth of the plant slows or ceases. High nighttime temperatures above 85 degrees can render the plant sterile.
The cotton plant flowers non-stop until inclement fall or winter weather arrives. The flowers appear white on the first day of opening. Pollination occurs during the morning or early afternoon hours. When pollination is successful, the flower turns pink. Once the flower is pollinated, it takes 55 days to develop a cotton boll. If the weather is cloudy and colder, the boll development will be delayed. Late in the season, boll development takes approximately 65 to 75 days.
Light and Growth
Cotton plants require full sunlight to adequately grow and produce bolls. If full sunlight is not received, the boll production will be dramatically reduced or stunted. The process of photosynthesis helps the plant to produce adequate sugars for foliage and boll development. Excessively cloudy or overcast days will reduce the light that the cotton plant needs to produce adequate sugars, so its cotton yield will be dramatically reduced.
Excessive morning rain can render the cotton plant sterile. The flowers fill with water, which disrupts pollination, and the plant does not get fertilised. Unfertilised blossoms fall to the ground. Saturated soil from rainy weather also causes the plant to not produce adequate cotton bolls. Spring rainfall can lower the soil temperature to below 15.6 degrees Celsius and delay or stunt cotton seed germination.
- University of Florida IFAS Extension: Cotton Growth and Development
- Mississippi State University: Weather and Cotton Growth: Present and Future
- Oregon State University: Cotton Planting
- University of Missouri Extension: Cotton Tillage and Planting Guidelines
- United Nations Conference on Trade and Development: Cotton Crop