Mix the remaining juice in the leftover milk bottle with water 10 times to water the flowers. There are more pouring times, the soil surface is slightly hardened, which can be solved by loosening the soil, and the organic matter in the milk can also improve the soil structure. However, when the whole bottle of spoiled milk is used for watering flowers, it must be fully fermented and matured, otherwise it will emit a strong odor and affect hygiene, and the acidity is too high, which will also stimulate the tender roots of flowers and cause poor growth.