Fresh and dry matter accumulation, general growth, and production of cotton, (Gossypium hirsutum L.) cv Gossica P-11, under conditions of limited potassium supply were evaluated in a greenhouse study. Potassium treatments consisted in the addition of 0, 1, 2, 3, 4, and 5 mM KCl to a complete nutrient solution that was supplied to cotton plants growing in sand culture. A level of 1 mM KCl was sufficient to sustain plant growth during the vegetative stage. However, when the fruiting period began, this level was not enough to support the fast growing rate occurring in bolls, and a general decrease in growth was observed after 94 days. At the final stage (140 days) there was a reduction in the fresh and dry matter accumulated in every plant part (root, stem, petioles, and leaves) as well as in the number and weight of reproductive structures. However, before 94 days no general depressive effects were observed at a level of 1 mM KCl for any of the variables evaluated. Plants growing in the absence of potassium remained vegetative the whole season and obtained lower values for fresh and dry matter accumulation at every sampling period.