Technical Abstract: Muskmelon fruit quality traits such as sweetness, aroma, and texture are directly related to potassium (K)-mediated processes such as photosynthesis and assimilate transport. However, soil-derived K alone is seldom adequate to satisfy plant K demand especially during the critical fruit growth and maturation stages. Supplemental foliar K application has been shown to mitigate this apparent deficiency, however, the suitability of potential K salts as foliar sources is still uncertain. In this study, we evaluated the effects of six different foliar K sources (potassium chloride - KCl, potassium nitrate – KNO(3), monopotassium phosphate – MKP, potassium sulfate – K(2)SO(4), potassium thiosulfate - KTS, and a glycine amino acid-complexed K, Potassium Metalosate - KM) on field-grown muskmelon (Cucumis melo) fruit quality parameters. Foliar K was applied weekly starting at fruit set and continuing to fruit maturity. Even though pre-plant soil K concentrations were very high, supplemental foliar K treatments resulted in generally higher tissue K concentrations. Soluble solids concentration (SSC), total sugars, and the human wellness compounds: ascorbic acid and Beta-carotene were generally higher in fruits from plots receiving supplemental foliar K compared to fruit from control plots. However, trends among K sources were not consistent except for KNO(3) which tended to result in poor fruit quality compared to control fruit. The results generally support previous observations that supplementing soil K supply with foliar K applications during fruit development and maturation can improve muskmelon fruit quality.