Latest Misconceptions About Greenhouse Vegetable Growing, Reviewed

In daily life, many vegetable growers make wrong judgments and take wrong actions in vegetable growing based on intuitive views or unripe experience. Below, the common mistakes and their solutions are corrected for growers.

Misconception one: believing that more fertilizer means more output

Many vegetable growers believe that heavily fertilizing greenhouse vegetable plots will bring high yields. In fact, excessive fertilization of vegetables very easily causes fertilizer damage. Solutions: First, in greenhouses that have been planted for more than 3 years, keep chicken manure and cow manure each within 2500 kg, and reduce chemical fertilizers by about 50%. Second, in plots with high total salt concentration, focus on applying cow manure, humic acid fertilizer and EM microbial fertilizer to raise the soil carbon-to-nitrogen ratio, loosen the soil and improve aeration, and relieve salt and fertilizer damage. Third, supplement boron, zinc and magnesium fertilizers to balance soil nutrients, creating conditions for lowering input and striving for sustained high yields.

Misconception two: believing that leaving more seedlings means a higher yield

Many vegetable growers tend to leave too many seedlings, believing that more seedlings can give high yields. In fact, because winter temperatures are low, light is weak, photosynthesis is poor, and carbohydrate synthesis is low, only a reasonable density can give high yields. Solutions: First, overwintering vegetables are best planted at a reasonable, sparse density. Second, to make full use of space, a management approach of dense planting in the early stage, thinning plants in the middle stage, and thinning branches in the late stage can be adopted, with spacing based on leaves and branches not being crowded, so as to raise total yield and total benefit.

Misconception three: believing that the higher the temperature, the faster vegetables grow

In fact, vegetables have an upper temperature limit, generally 25-32 degrees C. If the temperature is too high, respiration increases, the plant's internal operation and physiological activities become disordered, the plants grow leggy, vegetative and reproductive growth become unbalanced, and the yield instead declines. Solutions: First, set two ventilation openings in the greenhouse to cool it down in time. Second, manage according to the temperature required at each growth stage of each vegetable and the suitable temperature requirements at each organ's growth stage, to prevent high temperatures from producing long vines without fruit.

Misconception four: believing that vigorous vines mean the vegetables are growing well

Most people think vigorous vines mean a good crop, but in fact, with plenty of water the leaves flourish and the roots are necessarily shallow, nutrition is incomplete, yield is low, and excessive vegetative growth inevitably affects reproductive growth, so the yield instead drops. Solutions: First, at the seedling stage, aim for weak plants with deep roots, control water and control plant growth to promote rooting, so that the underground part absorbs about 60% of the photosynthetic products, while in the middle and late stages the underground and aboveground parts each absorb 50%. Second, in the early stage the plant body consumes 60% of the nutrients and reproductive growth accounts for 40%; in the middle stage each accounts for 50%; in the late stage reproductive growth accounts for 60%-70% and vegetative growth only 30%-40%, that is, ensure a certain assimilating leaf area in the early stage and control vines to promote fruit in the late stage to raise yield.

Misconception five: believing that spraying pesticide frequently means fewer diseases

Many vegetable growers spray pesticide once every 2-3 days in the middle and late stages of vegetable growth, believing that frequent spraying can prevent diseases from spreading. Solutions: First, identify the disease accurately and spray the right pesticide; preferably choose copper-containing and zinc-containing agents, which can not only kill bacteria but also enhance the plant's ability to resist pathogen invasion and promote crop growth. Second, improve the ecological environment; when branches and leaves are dense and ventilation is poor, spraying every day will not necessarily work well, so leaves should be thinned to lower the temperature. Third, for dead seedlings caused by soil-borne bacteria, focus on pesticide prevention at the seedling stage. If the source of disease is ignored and the seedlings become infected, then the disease breaks out later; once the pathogen has invaded the plant body, frequent spraying will not work well either.

Misconception six: believing that more cropping cycles mean more income

Many people think that after investing in building a greenhouse, the land should not be left idle, so they follow the main crop with a secondary crop and interplant the main crop with a secondary crop, planting many cropping cycles, but the result is often the opposite, with poor actual results and low benefit. Solutions: First, for the one big overwintering crop, it is best to grow one crop a year, while spring and autumn crops are best grown as two crops a year. For eggplant, pepper, tomato and cucumber, regenerated old plants can be kept for one more harvest, and when prices are low, pull up the plants and air the land. Second, each year leave a period in summer to deep-plow the land, let rain leach and press down salt, expose it to the sun to sterilize, close the greenhouse to kill insects, and mature the soil.