Applications of high rates of potassium are often made in an attempt to increase winter hardiness of bermudagrass [Cynodon dactylon (L.) Pers.] turfs. Research was conducted to evaluate two bermudagrass cultivars field‐grown on a high sand based soil mix and a native soil for the influence of applied K on cold resistance. A field study with six K rates ranging from 0 to 390 kg ha⁻¹ growing month⁻¹ were applied to ‘Tifdwarf’ and ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] established on a sand‐peat (9:1 by volume) and a Uchee loamy sand (loamy, siliceous, thermic Arenic Hapludult) during 1992–1994. Potassium chloride or K₂SO₄ were compared as sources of K and were applied with twice monthly N applications. Elemental soil and plant leaf tissue concentrations were measured periodically during the course of the study. By means of an electrolyte leakage (EL) method, predicted lethal temperatures were identified for rhizome samples removed from the field monthly from October through March of 1992–1993 and 1993–1994. Lethal temperatures estimated by EL were compared with those obtained by means of a recovery growth method. Extractable K in the growth media (12‐204 kg K ha⁻¹) and leaf tissue K concentrations (8.9–17.3 g K kg⁻¹ i DM) increased with increasing K rates. Application of high rates of K had no effect on predicted lethal temperatures or plant regrowtho Lethal temperatures for Tifdwarf ranged from °5.8 to −7.0°C, whereas those of Tifway varied from −6.8 to −8.4°C. High K rates appear to not increase bermudagrass rhizome cold resistance; therefore, there may be no benefit to using rates beyond those that provide sufficient K levels for normal growth.