The researchers studied how different planting dates affect the growth and yield of dryland millet. They found that planting on May 23 resulted in the highest grain and grass yield. Delayed planting dates led to shorter growth periods and slower growth rates of leaves and stems. Early planting dates showed rapid early growth rates, while late planting dates had rapid late growth rates. Overall, the best time to plant dryland millet is on May 23 in Zhangjiakou.