Potato (Solanum tuberosum L.) is one of the major economically important crops worldwide. Potato late blight disease (Phytophthora infestans (Mont.) de Bary) is the major bottleneck in potato production in Ethiopia. Selection of appropriate planting time is highly location specific and the most important subject in rain-fed potato production. However, there is no research recommendation pertaining to appropriate planting time with minimum fungicide application frequency due consideration of the environmental condition of high land area of Arsi (Kulumsa). Thus, field experiment was carried out.