Leaf water potential (LWP) measurements using a pressure chamber were used to determine optimum timing of the first irrigation following planting on Upland cotton. Previous studies have indicated that leaf water potentials are dependent on the vapor pressure deficit (VPD) of the surrounding air. As a result, the VPD was accounted for in the development of a Leaf Water Potential Index (LWPI). The field study consisted of three irrigation treatments with four replicates arranged in a randomized complete block design (RCBD). Targeted treatment thresholds were 0.15 LWPI (wet), 0.30 LWPI (medium), and 0.45 LWPI (dry). Timing of the first irrigation occurred at 36, 53,and 63 days after planting for the wet, medium, and dry treatments respectively. There were no significant lint yield differences between irrigation treatments.