“dry law” for tomatoes (kazarin method)
With periodic watering (even if rarely - once every one or two weeks, as most gardeners usually do), there is no incentive for growth at the roots of the tomato until the beginning of fruiting: moisture and nutrients for the development of the stem and leaf surface in the absence of fruit is enough.
Roots begin to grow only from the moment of a massive fruit set, that is, with a significant delay. As a result, fruiting is delayed, and the crop is reduced. In the absence of watering, the roots begin to look for moisture long before fruiting begins, grow in all directions, a powerful root system develops in a timely manner, capable of fully nourishing the plant not only during the growth of the stems, but also during the period of fruit filling. The crop in this case is always higher than that of plants with watering.

Of course, not everything is as simple as it seems at first glance. During normal planting, especially in greenhouses and in hot, dry weather, plants can not withstand and die. But this is a rare exception.
When planting seedlings from its lower half, I tear off all the leaves, dig up an oblong groove a little longer than half a stem under the shrub.
I pour half a bucket of compost into the groove (I prepare the compost without mineral fertilizers overfilling it, so I put it on demand, without fear of overfeeding), a handful — two wood ashes, 1 gram of potassium permanganate. Thoroughly mix everything.
Poured into the grooves on half a bucket of water. After absorbing moisture, the lower part of the stem is laid horizontally, orienting the tops to the north. If I plant seedlings without a lump of earth, then I will surely spread a clay talker, dipping half a stem into it, and then powder it with dry earth (for better connection with the soil).
More interesting: I sprinkle with a layer of earth 3-5 cm. I tie the upper part of the stem almost at a right angle to the stakes driven in right there (or later I tie it to a trellis). From above, I pour another half-bucket of water under the bush, trying to avoid moisture on the leaves.
That's all - no more watering the bushes during the whole season, right up to the harvest. It should be remembered that if plants are planted deeper, you will not get the effect of planting, since microorganisms are practically absent at a depth of 10–15 cm, and they mostly feed the plant.
The first time after planting, the plants are pleasing to the eye, they hardly fade even in the sun. But then, when drying in the holes of the earth, you see how the leaves of the tomatoes shrivel slightly. So I want to pour them at this time. And a careful vegetable grower here, of course, does not stand up - gives the plants moisture. And in vain. After all, what happens to the appearance of the plant is quite natural.
When the soil dries, it is a struggle for survival. The plant is looking for moisture, the roots are growing vigorously, energy, plastic substances are expended on it, which at this time are still not fully replenished. But it will take a little time, the tomatoes will get stronger, your pets will come to life and will be pleasing to the eye.
More interesting: The value of the method proposed by me lies in the fact that it allows you to grow a good harvest even from the most seemingly worthless seedlings - frail or overgrown. After 2-3 weeks, any "dead" seedlings become like a palm tree. It is only necessary for their owner to overcome the difficult psychological barrier and keep from watering.
Tomatoes without irrigation can be grown on any type of soil with any level in the area of groundwater. Sometimes in some greenhouses with muddy soil, the earth dries out and turns to dust. In such places even the weed dries. Here, sometimes, about once a month, it is necessary to maintain the planted plants with moisture.
In general, if you want to get the maximum yield of tomatoes, you can begin to water them no sooner than at the time of the mass fruit set, when the plant has already basically formed a root system. But I still do not water them, otherwise the fruits become watery and less tasty.
And without it, tomatoes grow so much that we process them only for juices, and there is enough harvest for the family for the whole year until the next harvest.