The Best Time, Frequency and Safe Interval for Fertilizing Vegetables

Vegetables are one of the essential foods in people's daily diet. Vegetables can provide various nutrients such as vitamins and minerals that the human body needs. So when is the best time to fertilize vegetables? How often should fertilizer be applied? How many days after fertilizing can they be eaten?

When is the best time to fertilize vegetables?

Fertilizers can be divided, according to different application periods, purposes and methods, into base fertilizer, seed fertilizer and top dressing, etc.

Base fertilizer is applied to the soil before sowing or transplanting, in combination with soil cultivation. It is usually based on organic fertilizers. Its role is to build up soil fertility and supply nutrients throughout the entire growth period of the plant. In order to give full play to the role of base fertilizer, different application methods such as broadcasting, banding and layered fertilization are often adopted according to soil characteristics, cultivation methods and the nature of the fertilizer.

Seed fertilizer is applied near the seeds at sowing or planting time, or mixed with the seeds when sown. Its purpose is to supply the nutrients needed for seedling growth. In China, there are various methods of applying seed fertilizer: mixing fertilizer with plant seeds before sowing, called seed dressing; soaking plant seeds in a dilute fertilizer solution before sowing, called seed soaking; dipping roots in fertilizer mixed with mud slurry when transplanting plants, called root dipping; covering the seeds with soil manure, burnt mud ash, etc. after sowing, called seed-covering fertilizer.

Top dressing is fertilizer applied during the plant's growth period. It aims to supplement and meet the plant's nutrient needs during growth. It is usually based on quick-acting chemical fertilizers and decomposed organic fertilizers. The main methods of top dressing include broadcasting, ring application and spraying. Combining fertilization with sprinkler irrigation and drip irrigation saves labor and fertilizer and gives good results. The fertilizers suitable for fertigation are mainly nitrogen fertilizers; phosphorus fertilizers are not suitable because they easily react chemically with salts in the irrigation water to form poorly soluble compounds that clog the small holes of sprinkler outlets.

How often should vegetables be fertilized?

Generally, top dressing can be applied once every 7-15 days. Usually top dressing is more frequent during the vigorous growth period, and less during the seedling stage and when approaching maturity.

How many days after applying compound fertilizer to vegetables can they be eaten?

Compound fertilizer mainly contains elements such as nitrogen, phosphorus and potassium. Different varieties have different nutrient content ratios. It is usually used as a base fertilizer and, in the later stage of vegetable growth, applied by flushing with water. After applying compound fertilizer, relatively speaking, the nitrite content in vegetables, especially leafy vegetables, is higher. After the fertilizer effect is released for a certain time, it will decrease somewhat after about 10 days. Also, harvesting vegetables later in the morning can reduce the nitrite content in vegetables, but when the leaf temperature is relatively high, it is not conducive to the storage of vegetables.