Tomato seedlings do not grow - take action

When growing such a wonderful crop as tomatoes, gardeners face a number of difficulties; the most common problem is that tomato seedlings do not grow.
Tomato seedlings require compliance with certain conditions, for example, compliance with a special temperature regime. Immediately after the appearance of the first shoots, the boxes with seedlings are put into a cool place for a week; during the day the temperature should be 16-18 degrees C, at night - 13-15 degrees C.
Then the temperature can be increased to 20 degrees C during the day and 16 degrees C at night. The specified temperature regime is observed until the third true leaf appears on the tomato (approximately 30-35 days). During this time, the seedlings are watered 3 times at the root, the third time watering is carried out on the day of the picking, an hour before it starts. The recommended water temperature for irrigation should be 20 degrees C.
After the appearance of two true leaves, the seedlings must be sprayed daily (in the morning) with low-fat milk (1 glass per liter of water), this procedure is a prevention of viral diseases.
On the 12th day after picking, the seedlings are fed with nitrophoska (1 tablespoon per 10 liters of water). Watering is carried out sparingly as the soil dries.
If, under the specified conditions, the tomato seedlings do not grow or grow slowly, then the tomatoes can be fed with a growth stimulant, for example, sodium humate. The solution is diluted to a consistency reminiscent of tea in color and the tomatoes are fed 1 cup per plant.
Two weeks before planting, tomatoes must begin to be hardened by placing them on a balcony or under an open window. First for 2-3 hours then for the whole day. The hardening temperature should not fall below 8-10 degrees C.