If you move a tomato, plant it deeper than it was. Fill in with soil, and it will grow more roots along the stem. You can even root cuttings from tomatoes. Pretty tough plants.

Thank you Susan! BTW, what is: "root cuttings from tomatoes"?

You can cut off a "branch" or "sucker" right at the point it comes off the main stem, making sure it is healthy - no brown or yellowing leaves. Some people get a rooting compound to dip the ends in, but I have always had good luck just putting it into a glass with about 3" of water, removing all leaves from just above the water line all the way down. Do not let the water level drop. It might take a week to see roots starting to form. I plant mine when the roots are at least 2" long. This is a good way to extend your crop if you live in the south where everything burns up midsummer.

Does somebody knows: A) how deep roots can grow? B) normally how close to the top of the soil roots grow?

Most of the roots are in the top foot, at least when planted in the ground. I've put them in some very big pots before but at the end of the season I have not dumped one out to see what the root structure looks like.

I'm sure they will grow into the top 2-3" especially when planted deep, or soil is mounded up around the stem, or when stems lie on the ground.

Can somebody confirm that if planted deep the part of a tomato stem transforms into primary root generating normal root hairs?

What if I will surround a stem of a tomato to a constant contact with soil about 1 foot above the ground and will leave the space if air of about 30cm between the ground and the upper soil pack. Will the stem convert to a primary root and develop new root system or I just will confuse and kill the plant?

@barmaleyka Why bother? Maybe if you have nothing else to do. Your plant as is will give you plenty of tomatoes! When they get ripe, they really get ripe waay to fast for you to eat them all. I'm not somebody who likes to can stuff. I make pasta sauce and freeze it, but that's the extent of it. Love those fried green tomatoes!

I can't confirm anything about your laying a stem in soil. You can root tomatoes, but I would cut the stems off that I want to root, let them develop roots in water, then plant them deep and leave them alone. But, that's just me.

Thank you toxcrusadr, now I found what to look for. There are a lot of information about it. I will read more and I think I incline to try.

I am contemplating about 1 inch of traditional pot soil to start the roots and then I will try 511 mix to finish roots. I will report to you buys if it works :)

IMO roots grow in search of nutrients for the plant. So if true you should be able to limit root growth by providing the nutrients need nearby.

This link will show how roots can/will grow in search of nutrients.

ROOT DEVELOPMENT OF VEGETABLE CROPS