Cotton is a globally significant fiber crop, providing a natural, renewable resource for the textile industry. Its cultivation is an annual process, completing the life cycle from seed to mature fiber within a single growing season. This development requires careful management, as the plant transitions through distinct stages that dictate fiber quality and yield. The entire cycle, typically spanning 140 to 180 days, is highly sensitive to environmental factors like temperature and moisture. Understanding these phases allows growers to optimize irrigation, nutrient delivery, and pest management.
Germination and Vegetative Growth
The cotton life cycle begins when seeds are planted into warm, moist soil, usually when temperatures reach 60°F (16°C) or higher. Adequate moisture initiates imbibition, where the seed absorbs water, triggering metabolic activity and the emergence of the radicle. Within five to ten days, a young seedling emerges, using its cotyledons until true leaves develop.
A deep taproot establishes itself simultaneously, securing water and nutrients, which allows cotton to tolerate relatively dry conditions. For the first four to six weeks, the plant focuses on vegetative growth, developing the main stem, true leaves, and lateral branches. This phase establishes the plant’s framework before shifting energy toward reproductive structures.
Squaring and Flowering
The transition to reproductive growth is marked by the appearance of “squares,” which are small, triangular flower buds enclosed by three protective bracts. This squaring phase begins about six to eight weeks after the seedling emerges. Development from a visible square to a fully open flower takes 21 to 25 days.
The square opens into a creamy white or pale yellow flower on its first day of bloom. The cotton flower is self-pollinating, and fertilization occurs rapidly. On the second day, the pollinated flower changes color to a pink or reddish hue, signifying successful fertilization.
Following this color change, the flower drops off, leaving the newly formed ovary to develop into the cotton boll. This cycle continues for several weeks, moving progressively up the main stem and along the fruiting branches.
Boll Formation and Fiber Maturation
The cotton boll is the plant’s fruit, a capsule developing from the fertilized ovary where the valuable fiber is produced. Following the flower drop, the young boll expands rapidly, lasting 50 to 70 days until maturity. Fiber development occurs in three distinct, overlapping phases.
The initial phase is fiber elongation, where the hair-like cells stretch rapidly, reaching their full length within the first 15 to 25 days after flowering. This elongation determines the final staple length, a primary measure of fiber quality.
The second phase is secondary wall thickening, lasting about 25 to 45 days. Layers of pure cellulose are deposited inside the fiber cell wall, establishing the fiber’s strength and maturity.
The final phase is desiccation and opening, known as dehiscence. As moisture decreases, the boll dries, the capsule splits, and the mature cotton fluffs out. The fibers are now ready for harvest.
Preparing for Harvest
As the bolls reach full maturity, the plant enters the final preparation stage for mechanical harvest. This phase is managed to ensure maximum fiber quality and harvesting efficiency. The primary practice is defoliation, applying chemicals to cause the leaves to drop prematurely.
Removing the leaves prevents green plant matter from staining the white cotton fiber during picking, which reduces its grade and market value. The absence of leaves also allows greater sunlight penetration, encouraging immature bolls to open fully.
Growers may also apply a desiccant, which dries the remaining plant matter. Once the majority of the bolls have opened and plant debris is minimized, the field is ready for the picking machinery.