Key Points on Sowing Time and Cultivation Methods for Greenhouse Tomatoes in Southern China

The tomato originated in South America and is widely cultivated in both northern and southern China. Tomato fruits are rich in nutrients and have a distinctive flavor; they can be eaten raw, cooked, or processed into tomato sauce, juice, or canned whole fruit. It is understood that tomatoes have a long harvest period and high yield, and the planting area is relatively large. In central and southern Guangdong Province, autumn planting can generally overwinter safely, and early planting can also fetch a good price. When should tomatoes be sown in southern China? What are the key points of greenhouse cultivation methods?

1. When should tomatoes be sown in southern China?

For greenhouse tomato cultivation in southern China, varieties with strong cold resistance and disease resistance should be selected. Tomatoes can be divided into two types according to growth habit, namely indeterminate growth type and determinate growth type (self-topping varieties). The indeterminate growth type has a long flowering period and high yield; the determinate growth type flowers early and concentratedly, with a concentrated and relatively short supply period. Tomato varieties suitable for planting in southern China include “Jinpeng No. 1”, “Yali 616”, “Xinong 2011”, “Maofen 802”, and others.

Greenhouse tomatoes are mainly supplied during the Spring Festival period, and the suitable sowing time is from mid-to-late August to early September.

2. Key Points of Greenhouse Cultivation Methods for Tomatoes in Southern China

1. Sowing

Put the nutrient soil into nutrient pots, place the nutrient pots in the beds, ensure sufficient moisture in the beds, then place the sprouted seeds into the nutrient pots, one seed per container, cover with soil, and keep the seedbed temperature at 25-30°C. From sowing to before emergence, the greenhouse does not need ventilation. After the seedlings emerge completely (when the emergence rate is higher than 80%), ventilate to harden the seedlings, avoiding excessively high temperatures in the greenhouse. The daytime temperature should be controlled at 25-30°C, and the nighttime temperature at 15-20°C. From seedling emergence to before the first true leaf appears, particular attention should be paid to controlling the day-night temperature difference to prevent seedling legginess. After 7-8 true leaves appear, transplanting can be carried out. One week before planting, pay attention to ventilation, lower the seedbed temperature, water less, and harden the seedlings at low temperature.

2. Planting

Tomatoes have a long growth cycle and high fertilizer requirements. Therefore, sufficient base fertilizer needs to be applied before planting: apply 2000 kg of fully decomposed farmyard manure per 667 sq m, along with trace element fertilizers, incorporated during plowing; then apply 100 kg of ternary compound fertilizer per 667 sq m, scattered on the soil surface after plowing; in addition, apply 100 kg of soybean cake per 667 sq m near the planting holes. When planting, choose a sunny day, select healthy, disease-free strong seedlings, and plant in wide and narrow rows with a plant spacing of about 45 cm, at 2000 plants/667 sq m. After planting, water thoroughly and loosen the soil appropriately.

3. Fertilizer and Water Management

(1) Irrigation Requirements

During the seedling hardening period, that is, before the first cluster of fruit sets, no watering should be done, to ensure the roots grow downward; before the flower buds of the third cluster of fruit just open, before the second cluster of fruit reaches the size of a broad bean, or before the first cluster of fruit reaches the size of a walnut, watering should not be done. 3-5 d after planting is completed, begin the first watering. Before the first cluster of fruit sets firmly, tomatoes are mainly in vegetative growth. When the seedling recovery water and planting water have been applied sufficiently, basically no watering or topdressing is needed at other times.

(2) Tomato Fertilization Requirements

The demand for nitrogen and potassium is relatively large, and a moderate amount of phosphorus is also needed. Once the first cluster of fruit has set firmly, 20-30 kg/667 sq m of potassium sulfate compound fertilizer can be applied along with watering. When the second and third clusters of fruit are rapidly expanding, topdressing should be done in time, generally 3 times, with 20-25 kg/667 sq m of potassium sulfate compound fertilizer. When the fruit is expanding, spray 0.2% monopotassium phosphate on the leaves 2-3 times, which can effectively prevent pests and diseases and effectively promote fruit development.

4. Pest and Disease Control

Common tomato diseases mainly include gray mold, early blight, and stem rot, while pests mainly include aphids and ladybugs.