When should tomatoes be started from seed? Generally around January.
SummaryTomatoes are suitable for starting from seed between late December and mid-January. The specific sowing time can be decided according to the local climate. Generally, when the soil temperature is above 13°C, they can be sown and started from seed. If they are grown in succession with other crops, the appropriate sowing time needs to be chosen according to the harvest time of the previous crop.
1. Sowing time
Tomatoes are suitable for starting from seed from late December to mid-January. Generally, when the soil temperature is stable above 13°C, they can be sown and started from seed. The suitable sowing time and sowing method can be chosen according to the temperature in different regions. In early spring, tomato seedling raising depends on the insulation level inside the greenhouse and the planting time outside the greenhouse. Usually, the planting time in a greenhouse is 2 months earlier than outside. For example, if planting outside the greenhouse is in mid-May, the greenhouse planting should be in mid-March. The tomato seedling age is about 60 days.
If grown in succession with other crops, the sowing time needs to be chosen according to the harvest time of the previous crop, and the method of waiting for the seedlings with the land should be adopted as much as possible.
2. Seedling raising techniques
1. Seed soaking and disinfection
Usually, the seed amount per mu is between 30-50 grams. Before sowing, sun the seeds for 2 days, which can increase the germination rate. Then soak them in warm water at about 55°C for 15 minutes, stirring clockwise, then add cold water. After the water temperature drops to about 35°C, soak the seeds for 6-8 hours, which can effectively avoid the occurrence of viral disease. Then soak them in a 10% trisodium phosphate solution for about 50 minutes. After soaking, wash off the seed coat mucus with clean water, drain the seeds, and after drying them, they can be sown.
2. Establishing the seedbed
On average, each mu requires 10 sq m of seedbed. Then apply 100 kg of fully decomposed organic fertilizer, 100 grams of Keshade Sanqian, and 500 grams of Yongzhuang fertilizer, spread them evenly and shallowly till 12 cm, then level the seedbed and water it thoroughly. For disinfecting the seedbed soil, mix 58% metalaxyl·mancozeb and 70% thiophanate-methyl at 1:1, then after mixing with 10 grams of pesticide per sq m and 5 kg of filtered fine soil, stir evenly.
When sowing, use two-thirds of the nutrient soil to level the seedbed as the base soil, sow the seeds evenly, and after sowing, cover the seeds with one-third of the soil to a thickness of 0.8-1 cm. To promote early emergence, cover the seedbed with plastic film, and keep the daytime temperature at about 30°C, with the maximum not exceeding 33°C.
When one-third of the seedlings have emerged, the plastic film can be removed. After the seedlings are fully grown, lower the temperature to about 25°C to avoid excessive growth. You can use 10 grams of 68.75% famoxadone plus mancozeb or 30 grams of 70% propineb plus 20 ml of 72.2% propamocarb hydrochloride mixed with 15 kg of water to continuously spray the seedlings to prevent damping-off, early blight, and sudden wilting disease during the seedling stage.
3. Seedling separation
When the seedlings grow to 2 true leaves and 1 heart leaf, it is an important period for seedling separation. Prepare the nutrient soil in advance. First remove the top 5 cm of soil and clear away herbicide residues. The formula for preparing 1 cubic meter of nutrient soil is: use field topsoil, mix with 40% decomposed organic fertilizer, 90 grams of propineb, 10 kg of biological bacterial fertilizer, and 500 grams of Yongzhuang, stir evenly and store well.
Before seedling separation, dip the seedling roots in 1000 times Haijingling. About 3 days after seedling separation, control the temperature between 28°C-30°C. After the seedlings recover, control the temperature between 22°C-25°C. Note that spraying 2% propamocarb hydrochloride once before seedling separation can prevent sudden wilting disease. After the seedlings recover, irrigate the roots with 500 times Yongzhuang solution plus 500 times Teyougen solution, which can prevent damping-off and also promote more root growth in the seedlings.
4. Flower bud differentiation
Tomato flower bud differentiation starts from the 3rd true leaf, then stops differentiating at the 9th true leaf. Generally, by the 7th true leaf, the first 3 trusses of fruit have already completed differentiation. If flower bud differentiation is poor, it is easy to cause deformed flowers and deformed fruits later, so the success rate of flower bud differentiation during the seedling stage will affect the early yield. During this period, spraying 25 grams of Huaguoduo plus 8 grams of Haijingling at 3-5 true leaves is beneficial for promoting flower bud differentiation.
5. Pest and disease control
Common pests during the seedling stage include aphids, whiteflies, and leafminers. They can be controlled by spraying 5 grams of 70% imidacloprid and 10 grams of 40% Wanling mixed with 15 kg of water. Common diseases during the seedling stage include viral disease and stem base rot. At 3-4 true leaves, spray 25 ml of 4% ningnanmycin, 4 ml of Kangpu zinc, 15 ml of Longdeng Youduoboron, 8 grams of Haijingling, and 100 ml of honey mixed with 15 kg of water.
To control stem base rot, 2 days before planting, spray the seedbed with 9 grams of Yikuaijing, 10 grams of Keshade Sanqian, and 8 grams of Haijingling mixed with 15 kg of water.
6. Requirements for planting seedlings
The seedling age is about 90 days, with the main stem half purple and half green, of which 70% have flower buds, the stem diameter is 0.6 cm, and the root system is well developed with no pests or diseases.