Re‐establishment of an annual bluegrass putting green following simulated winterkill

A common method of re‐establishing putting greens following winterkill is to vertically mow and apply seed. There is very little information available on when spring seeding should occur and what creeping bentgrass ( Agrostis stolonifera L.) cultivars should be used in the field. The objective of this study was to evaluate spring establishment rate of creeping bentgrass and annual bluegrass [ Poa annua var. reptans (Hauskn.)] seeded three consecutive weeks in the spring of 2023 and 2024. Seed entries included creeping bentgrass cultivars, ‘Penncross’, ‘Pure Distinction’, ‘Declaration’, ‘Penn A‐4’, one annual bluegrass seed, ‘Two‐Putt’, a 50/50 (w/w) Pure Distinction and Two‐Putt mix, and a non‐seeded control. To simulate winterkill, non‐selective herbicide was applied twice prior to seeding and plots were vertically mowed in two directions. Seed was applied at 2 lb 1000 ft −2 three consecutive weeks once soil temperatures reached a daily average of 45°F at a 2‐inch depth. Digital image analysis was collected for 5 weeks during the establishment period to assess turfgrass cover. Seeding date one had the highest turfgrass cover at the beginning of data collection for two rating dates in 2023 and one rating date in 2024. By the end of the study, seeding date was not significantly different. In 2023, Penn A‐4 and Penncross had the highest turfgrass cover, but differences were small and biologically insignificant. In 2024, there were no differences among creeping bentgrass cultivars, and in both years, Two‐Putt annual bluegrass was one of the worst establishing entries.