Greenhouse Vegetables Not Growing Well? An Expert Explains the Key Cultivation Techniques

Greenhouse vegetables refers to vegetables grown under plastic film-covered greenhouses. The market season of the vegetables can be controlled artificially. In recent years, as people's living standards have improved, the pursuit of a higher quality of life has also grown ever higher, which has driven the rapid development of agricultural greenhouses. More and more farmers are beginning to explore and try growing vegetables in greenhouses. However, quite a few greenhouse vegetable growers report that their greenhouse yields are not high and that diseases are also numerous. In this regard, experts point out several key points of greenhouse cultivation techniques as follows:

1. Determine a reasonable planting time.

The level of benefit from greenhouse vegetables depends to a large extent on how early or late the planting time is. For off-season vegetables, the period around spring is the peak time for benefit, so the planting time should be set on the basis that the period around spring is the period of highest yield. In places that have developed from the original one crop a year to the current 70% two crops a year, the planting periods are roughly as follows: for one crop a year, the planting period is in early to mid-October; for two crops a year, the first crop is in early to mid-July, and the second crop is planted from December to January of the following year. With such planting times, the benefit is relatively high.

2. Choose high-yield, disease-resistant improved varieties.

Improved varieties are the internal cause of increased yield. High-yield cultivation techniques cannot be separated from improved varieties in the first place. Growing off-season vegetables using facilities such as greenhouses relies on abundant light and heat resources, and mainly involves growing several major categories of vegetables and melons such as tomatoes, cucumbers, eggplants, peppers, beans and muskmelons. Choosing good varieties generally increases yield by 10%-20% and increases benefit by more than 10%.

3. Reasonable greenhouse type.

Greenhouses are divided into 5 types. In vegetable cultivation, the greenhouse type should be chosen according to the different temperature requirements of the vegetables, or in other words, the vegetable types to be grown should be determined according to one's own greenhouse type. Only in this way can the ideal vegetable yield be obtained.

4. Formula fertilization.

Fertilization is the foundation of increased yield. High vegetable yields also remove more nutrients, so increasing the application of base fertilizer is an important safeguard. Generally, for a yield of 10,000-20,000 jin per mu, apply 10,000-20,000 jin of fully decomposed organic fertilizer as base fertilizer, and it must also be combined with quick-acting chemical fertilizers so as to achieve a combination of slow-release and quick-acting nutrients. Quick-acting chemical fertilizers are mostly three-element compound fertilizers and diammonium phosphate. In addition, a certain amount of trace-element fertilizers such as iron, boron and molybdenum and medium-element fertilizers such as calcium and sulfur should also be applied as base fertilizer. Once the fruiting stage is entered, a certain amount of fertilizer should also be applied by flushing with water.

5. Selection of greenhouse film.

The choice of greenhouse film has a relatively large impact on yield, and further affects the benefit of cultivation. Greenhouse film is divided by material into polyvinyl chloride, polyethylene and EVA film, and by function into long-life anti-drip film, semi-drip film, fog-dispersing film and so on. It should be selected reasonably according to the different types of vegetables. For growing cucumbers, polyvinyl chloride film should be chosen; cucumbers grown with this film have a proper color. For growing tomatoes, polyethylene or EVA film should be chosen, because tomatoes belong to the warmth-loving and light-loving type but are also relatively tolerant of weak light and low temperature, and both of these films can meet the growth requirements of tomatoes. For growing eggplants, EVA film should be chosen; this film has high light transmittance, resistance to aging, good anti-drip properties and fog dispersion, and eggplants color well.

6. Grafting technique.

Vegetable grafting is an effective measure to increase yield. By relying on the resistance of the rootstock, it can increase root absorption and prevent certain stubborn diseases, and it is even more practical in old vegetable-growing areas. The types grafted include cucumber, eggplant, pepper and tomato. The grafting methods include approach grafting, splice grafting and cleft grafting. For example, grafting cucumber onto black-seed pumpkin or white-seed pumpkin not only solves cucumber Fusarium wilt but also increases the absorption range of the root system, improving drought resistance and cold resistance. Grafting eggplant onto Torubamu (Solanum torvum) achieves a control effect of more than 95% against Fusarium wilt and Verticillium wilt, and also fundamentally solves the damage caused by root-knot nematode disease. Pepper Phytophthora blight is a devastating disease, and it can basically be controlled through grafting.

7. Ridge cultivation.

Ridge cultivation is an important measure in vegetable production, and it is even more significant in off-season deep-winter cultivation. It can increase the light-receiving area of the soil, raise soil temperature, and facilitate operations such as watering and fertilizing. It is a good measure adopted in the cultivation of many kinds of vegetables. Ridge cultivation of peppers can significantly reduce the occurrence of root rot and Phytophthora blight.

8. Full plastic film mulching.

Plastic film mulching is another major technique in greenhouse vegetable cultivation. It can effectively reduce humidity inside the greenhouse, lower the conditions for disease occurrence, increase soil temperature, make fruit color better, and reduce the number of pesticide applications. Plastic film can reflect light and increase the intensity of light on the leaf surface.

9. Two films sandwiching one straw mat.

Adding a layer of floating film over the straw curtain is another yield-increasing measure adopted in the last five or six years. It is especially significant in deep winter on rainy and snowy days. Compared with no floating film, it increases the nighttime temperature by 1-2°C, and also greatly reduces the risk of labor intensity and extends the service life of the straw curtain.

10. Integrated pest and disease control techniques.

In greenhouse vegetable production, because the field microclimate is changed, various diseases occur more severely than in open-field cultivation. Doing a good job of pest and disease control is the key to achieving high yields. Cucumbers have 27 kinds of pests and diseases, tomatoes 43 kinds, sweet (hot) peppers 21 kinds, and beans also several kinds. Timely and accurate prevention and treatment of these pests and diseases is very important. In accordance with the requirements of standardized production, agricultural measures, physical measures and biological measures should be adopted, and high-efficiency, low-toxicity and low-residue pesticides should be used scientifically.