Soak the selected superior seeds in warm water at 50℃ for one day and night, and take them out to dry the surface after the absorbed water expands, which can be used for sowing. The sowing date is from Qingming to Grain Rain (mid-April), and the temperature is 15 ~ 20℃, which is too early and the ground temperature is low, so the seeds are easy to rot in the soil. It's too late, the seeds can't mature, which affects the yield and quality.

Suitable sowing spacing is 50 ~ 70cm, and ditch depth is 5 ~ 6cm. Spread the seeds evenly in the ditch, cover the soil with 3cm, press slightly, and emerge about 10 days after sowing. The north is dry, so water it before sowing, but not after sowing, so as to avoid the hardening of topsoil affecting the emergence.