The occurrence of widespread potassium (K) deficiency across the Cotton Belt has focused interest on the possibility of foliar feeding cotton with K to supplement traditional soil application methods. Foliar applications of K may offer the opportunity of correcting these deficiencies more quickly and efficiently, especially late in the season when soil application of K may not be effective. Field research during the last few years has shown that foliar-applications of KNO₃ can alleviate K deficiency and significantly increase yield and fiber quality. However, a Beltwide study in 1991 at twelve sites from North Carolina to California, in which soiland foliar-K fertilization was evaluated, gave very variable yield results with significant increases from foliar K at four out of the twelve locations. These results indicate the critical need to improve our understanding of the best timing, frequency and rates of applying foliar potassium, and the underlying physiological explanation of how and why this practice works. Currently, there are no definitive studies available on the usefulness of foliar-applied KNO₃. Results to date indicate that foliar application of KNO₃ appears to be a useful production practice for supplementing preplant soil applications of potassium fertilizer especially when K deficiency symptoms occur and soil and petiole tests show a low K status.