The first stage

Place the picked and sorted Overlord flowers evenly on the material frame. Only when the initial temperature of the drying room is raised to about 55 degrees can the flowers be pushed into the drying room. Dry bulbs were set at 55°C and wet bulbs were set at 38°C. The room temperature should be keep for 4–6 hours, afterwards the flower will enter into a softening period.

The second stage

The temperature of the drying room should be gradually increased from 55 degrees to 60 degrees for dry bulbs, and increased from 38 degrees to 42 degrees for wet bulbs. The heating up time should be controlled within 2 hours and cannot the temperature cannot exceed 60 degrees. After initial, moderate drying and strong dehumidification process for 9-12 hours, the overlord flower basically could reaches 70% dryness.

The third stage

The heating stage of the dry bulb, from 55-60°C, is controlled for 4-6 hours . In this stage, the wet bulb temperature is set at 46°C to facilitate the temperature increase. After the third stage, the overlord flower could basically reaches 80% dryness.

The fourth stage

For the mandatory drying period, the temperature of the dry bulb is set to 75°C, and the wet bulb’s temperature is set to 50°C. The temperature should not exceed 80°C. After 2-4 hours, the moisture content of the overlord flower is about 12%. After the overlord flower is dried and colored, the flower could be released out of the drying room. The advantages of heat pump dryers are intelligent temperature control and automatic moisture removal. The average disposal cost for per kilo of dried flowers is about 10 cents.