When do tomatoes grow seedlings? Seedlings are usually raised around January.

Tomato seedlings are suitable to be raised from the end of December to the middle of January, and the specific seedling time can be determined according to the local climate, when the ground temperature is more than 13 ℃, the seedlings can be sown and raised if they are continuous cropping with other crops, the suitable seedling time should be selected according to the harvest time of the previous crops.

I. Seedling raising time

Tomato seedlings are suitable to be raised from the end of December to the middle of January. Generally, the seedlings can be sowed when the local temperature is more than 13 ℃. The suitable sowing time and sowing method can be chosen according to the temperature in different areas. Tomato seedling raising in early spring depends on the degree of heat preservation in the greenhouse and the planting time outside the greenhouse. The planting time in the greenhouse is usually 2 months earlier than that outside the greenhouse, such as planting in the middle of May outside the greenhouse. The greenhouse will be planted in mid-March, and the tomato seedlings will be about 60 days old.

If continuous cropping with other crops, it is necessary to choose the seedling time according to the harvest time of the previous crop, and try to adopt the method of waiting for seedlings.

2. Seedling raising techniques

1. Seed soaking and disinfection

Usually the amount of seeds per mu is between 30 and 50 grams. Drying the seeds for 2 days before sowing can increase the germination rate, then soak in warm water of about 55 ℃ for 15 minutes, stir clockwise, add cold water, and wait for the water temperature to drop to about 35 ℃. Soak the seeds for 6-8 hours, which can effectively avoid the occurrence of virus disease. Soak in 10% trisodium phosphate solution for about 50 minutes, and wash off the seed coat mucus after soaking. Drain the seeds, dry them, and then sow them.

2. Establish a seedbed.

An average of 10 square meters of seedbed is needed per mu, then 100kg of mature organic fertilizer is applied, 3000100g of manure can be killed, 500g of brave fertilizer is applied, 12cm is removed and turned shallowly, then the seedbed is leveled and watered thoroughly, and the soil of the seedbed is disinfected with 58% manganin and 70% methyl thiophanate at 1:1. Filter the fine soil according to 10g and 5kg per square meter, then stir evenly.

During sowing, 2/3 nutritious soil was used as cushion after leveling the seedling bed, and the seeds were evenly sown. After sowing, 1/3 soil was used to cover the seeds with a thickness of 0.8-1cm. In order to promote seedling emergence as soon as possible, the seedbed should be covered with plastic film. The daytime temperature should be kept at about 30 ℃, and the highest should not exceed 33 ℃.

When 1/3 seedlings are unearthed, the plastic film can be removed, and after the seedlings have grown together, the temperature can be reduced to about 25 ℃ to avoid overgrowth. 68.75% oxazolidone manganese zinc 10 grams or 70% propicolone zinc 30 grams plus 72.2% aldicarb hydrochloride 20 ml mixed with water 15 kg constantly spray the seedlings to prevent seedling blight, early blight, quenching disease and so on.

3. Divide the seedlings

It is an important period for seedling separation when seedlings grow to 2 leaves and 1 heart. In order to prepare nutritious soil in advance, we must first remove the surface soil of 5cm and remove the residue of herbicides. The formula of 1 cubic meter of nutritious soil is: using field topsoil, mixing 40% of rotten organic fertilizer, 90 grams of propionate zinc, 10 kg of biological fertilizer and 500g of Yongzhuang, stirring and storing evenly.

The seedlings were dipped in the roots with 1000 times sea elves before seedling division, the temperature was controlled between 28 ℃-30 ℃ about 3 days after seedling division, and the temperature was controlled between 22 ℃-25 ℃ after retarding seedlings. Spraying 2% of aldicarb hydrochloride once before seedling division could prevent and cure stunting disease, and irrigating roots with Yongzhuang500x solution plus Teyougen solution after seedling retardation could prevent and cure root blight and promote multiple rooting of seedlings.

4. Flower bud differentiation

The flower bud differentiation of tomato starts from the third true leaf, and then stops differentiation at the 9th true leaf. Generally, by the seventh true leaf, the first three ears have already differentiated. If the flower bud differentiation is poor, it is easy to cause abnormal flowers and abnormal fruits in the later stage. Therefore, the success rate of flower bud differentiation in the seedling stage will affect the yield in the early stage. During the period, 25 grams more flowers and fruits plus 8 grams of sea elves can be sprayed on 3-5 true leaves. It is beneficial to the differentiation of flower buds.

5. prevention and control of diseases and insect pests

The common pests in the seedling stage are aphids, whitefly, Liriomyza huidobrensis, etc., which can be sprayed with 5 grams of 70% imidacloprid and 40% Wanling 10 grams with 15 kg of water. The common diseases in the seedling stage are virus disease and stem rot. 4% Ningnanmycin 25 ml, kangpu zinc 4 ml, Longdenyou polyboron 15 ml, sea elves 8 g, honey 100 ml and water 15 kg can be sprayed in 3-4 true leaves.

In the prevention and control of stem rot, you can spray the seedling bed with 9 grams of Yikuangjing, 3 thousand 10 grams of sea elves and 15 kilograms of water 2 days before planting.

6. Requirements for planting seedlings

The seedling age is about 90 days, and the main stem is purple and green in half, of which 70% has buds, the stem is thick in 0.6cm, the root system is well developed and there are no diseases and insect pests.