A conditioning mechanism is placed forwardly of the cotton harvesting mechanism on a cotton harvester. Opposing elements compress portions of the cotton plant to compress the cotton bolls and deform the cotton boll hulls. The deformation loosens the cotton fiber relative to the hulls to improve the ability of the harvesting mechanism to harvest the seed and fiber. In one embodiment, differential surface velocity of the opposing elements improves boll opening and fiber orientation for more effective spindle contact.