Plant leaves have tiny pores on both sides, and different plants have many pores. For example, drought-resistant plants have fewer stomata. Stomata can breathe and absorb water. You can use this to fertilize the leaves, that is, spray the appropriate concentration of fertilizer solution directly on the leaves, but be careful not to be too thick and the fertilizer composition should not be too single. If you don't understand, you'd better know the habits of your plants.