Rainwater is one of the important water sources for plant growth. When raindrops fall into the ground, seedlings will absorb water from the soil through their roots. The supply of water is very important for the growth of seedlings, and water is the basis of photosynthesis and nutrient absorption of plants. The supplement of rainwater can meet the growth needs of seedlings, make them absorb enough water and nutrients, promote cell division and elongation, and thus make seedlings grow healthily.