A Complete Guide to Watering Precautions for Summer Vegetables

In the hot summer, especially in July when temperatures are high and the weather is muggy, water evaporates in large amounts. So, what are the precautions for watering vegetables in summer?

There is a saying in summer that “a small drought every three days, a big drought every five days.” Vegetables grown in open fields will show signs of drought if not watered for 3-5 days. For vegetables in protected cultivation, watering replenishes the water lost to evaporation under high temperatures, meets the water needs of the vegetables, and at the same time lowers the temperature inside the greenhouse.

1. Timing of watering

It is best to water in the morning, starting at dawn, and stop watering after 9-10 o'clock when the sunlight becomes particularly strong. As the temperature rises and water evaporates, it will carry away heat from the vegetable beds, making the temperature inside the greenhouse 3-5°C lower than in the open field. Water every 3-4 days, watering alternate furrows (alternating between the large and small rows), and do not water too much at once. The principle is to increase the frequency of watering and reduce the amount of water each time.

2. Apply topdressing promptly while watering

Decide the type and amount of topdressing based on the vegetable growth and the harvest yield. For melon and fruit vegetables, during the peak harvest period, apply a water-soluble fertilizer with medium nitrogen, low phosphorus, and high potassium, using 15-20 kg per mu. While watering alternate furrows (rows), for watering combined with topdressing, you can also adopt the method of applying clear water once, then fertilizer water once, in small amounts and multiple times. In addition, do not let rainwater flow backward into the greenhouse during heavy rain. If it is a large arch shed with the film removed, drain water promptly after rain and dig a drainage ditch in front of or to one side of the shed.

3. What is “watering the garden after waterlogging”?

Vegetables like water but fear waterlogging, especially at noon on hot summer days, if a thunderstorm (commonly known as hot rain) suddenly occurs, in addition to draining water promptly, you must water again with well water after the hot rain. This is because well water is relatively cool; watering with well water can reduce surface heat and at the same time reduce soil compaction. This is the so-called “watering the garden after waterlogging.” It is especially important for melon and solanaceous vegetables produced in summer, followed by onions and chives.

If a thunderstorm occurs at noon and water is not drained promptly, oxygen in the soil will be insufficient, root respiration will be inhibited, affecting the absorption of water and minerals. At the same time, anaerobic bacteria become active, causing inorganic acids and organic acids to accumulate in the soil, raising the soil solution concentration and producing toxic reducing substances such as hydrogen sulfide and ammonia, which poison and kill the roots. Therefore, when a thunderstorm occurs at noon in summer, you must carry out “watering the garden after waterlogging.”

If watering around noon, it is best to drain off the initial portion of water whose surface temperature is too high, which has a good effect on reducing high-temperature heat damage.

For onions and chives, waterlogging is more likely to cause plant death, commonly known as “melting seedlings.” That is to say, after heavy rain, drain water promptly; if conditions permit, carry out watering the garden after waterlogging, and if conditions do not permit, still drain away the rainwater. For plots without drainage conditions, dig a soil pit on one side of the field as temporary drainage, which has a certain effect on alleviating waterlogging damage.