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Losses of yield and stand of ‘Coastal’ bermudagrass (Cynodon dactylon L. Pers.) due to inadequate K fertility have been observed numerous times. Stand deterioration has been attributed to “winter-kill”, disease, and lack of “physiological hardening” of the plants. Since all the aerial parts of the bermudagrass plant die when temperatures are as low as -2 to -3 C, underground stems (rhizomes) are important for maintaining and generating growth in the spring. Studies were conducted to investigate the effects of K fertility practices on rhizome production and rhizome regrowth reserve as related to certain stand and tissue characteristics. Old P and K factorial rate studies on Darco (Grossarenic Paleudult; loamy, siliceous, thermic) and Cuthbert (Typic Hapludult; clayey, mixed, thermic) soils were used. Annual fertility rates used on prior experiments were 0, 112. and 224 kg/ha K, 0 to 136 kg/ha P, and 364 to 504 kg/ha N. The influence of residual P and K fertility on stand ratings, rhizome production, and Ca, Mg, and K content of the forage was measured. Stand ratings in the spring were found to be related to rhizome production. The first increment of 112 kg/ha of K increased rhizomes 800 kg/ha on the Darco soil. Rhizome production required higher rates of K on the Cuthbert soil which gave a response of 1,500 kg/ha of rhizomes to the highest K rate used. Lowering the K rate resulted in lower K in the tissue and an observable loss of vigor in the root system. Depending on the soil K reserve, production levels ,and previous fertility practices, Coastal bermudagrass hay meadows on which K fertility levels are inadequate may exhibit the characteristics described above.