Abstract Maize ( Zea mays L.) productivity in Central Texas is highly vulnerable to erratic rainfall and high temperatures during the growing season. Optimizing planting date is therefore essential for maximizing grain yield under these challenging climatic conditions. This study evaluated the impact of planting date on maize grain yield across 5 site‐years (2020–2023) under rainfed conditions. Maize was planted across seven‐time windows, spanning from early March to late April. Results demonstrated that planting during the first three weeks of March consistently produced the highest yields, averaging above 8.1 Mg ha − 1 . In contrast, delaying planting into April led to a sharp decline in yield, with late‐April plantings yielding as low as 3.26 Mg ha − 1 . A piecewise linear model identified the 73 rd ± 2 day of the year (March 14 ± 2 days) as the breakpoint threshold planting date, after which yield declined at a rate of approximately 15 kg ha − 1 day −1 . Weather variables were strongly associated with yield outcomes, particularly during the peak vegetative growth stage (31–60 days after planting). Growing degree days and cumulative solar radiation were negatively correlated with yield during peak vegetative and reproductive growth stages, while both precipitation amount and frequency were positively associated. Principal component analysis further confirmed that cooler temperatures and adequate mid‐season precipitation were key drivers of high grain yield. These findings highlighted the importance of timely planting in early March to avoid mid‐ as well as late‐season heat and moisture stress in Central Texas.
Sapkota et al. (2026) studied this question.