2W。
The wavelength bands that plant light supplement can promote plant growth are basically biased towards red and blue. Therefore, we should choose LED plant growth lamps with red and blue bulbs to fill the light. The ratio of red to blue is actually 7:1, 7:2 and 7:3. There are detailed studies abroad, and there are some differences in the demand for each kind of meat, but the approximate ratio is similar. This need not be too entangled.
Precautions for plant fill light
The distance between plant growth light and plant is 2.5m-3.5m, the minimum height of 9W plant growth light is 1.5m, the minimum height of 3W plant growth light is 2m, and the minimum height of 6W plant growth light is 3-4m.
24W plant supplementary lights need to be 5cm away from plants, with or without sunlight for no more than 12 hours. When plant growth lights are lit at night, they tend to attract insects and small animals, so it is best to close the door of the greenhouse.