Is it true that tomatoes have one main root stem which can go down up to 4-5' and if it is damaged during transplant the plans still grow side roots and never as deep. The plant with the main root suppose to produce better. If this is true, what about plants made of suckers? Do the develop the main root? Sorry it this theory is wrong - I heard it from a single person and a quick search on the web gave me nothing of value on the subject.

When you dig up a tomato at the end of the season you will find that the rootball is right where you left it. From there roots will go out all directions searching for water.
If you planted deep, there will be lesser roots formed all along the stem that you buried, as the hairs on the stem turned into roots.
If you trenched sidewise, there will be the original rootball, lesser roots along the buried stem, and also a second major rootball will have formed at the bend/base of the plant.
If you severely damaged the stem, and effectively have no rootball to start, it would form a rootball at the base just like a trenched plant. No, I don't believe it would reach as deep, at least in my soil. There is a finite time to grow.
However, I don't think the depth of the roots matters much either, not here. The warmer upper soil is where the plant gets the nutrients, not down deep in the cool earth. It really depends on the unique environment - sun, soil, and water. In a sandy soil down south with a lot more heat, the roots should go deeper - unless it is being watered all the time and it doesn't need to find water.

Plants made from suckers do not develop a tap root. If you want a tap root you must start from seed.

For my containers I think fibrous/feeder roots are best.

In one of my rows in the main inground garden I want to try and encourage a tap root. I am starting a few plants for a late planting directly in 5 x 6 inch pots. I believe the 6 inch depth will help the plant create a tap root. I am in a hot dry climate and think the plants will benefit from a tap root because the soil is moister down deep.

I am preparing this row by loosening the soil about eighteen inches down with an earth auger and blending in some composted steer manure. The row is drip irrigated to encourage deep watering.

Refer to post #20 in viewtopic.php?t=3455 The quote in post #20 refers to a study where plants with undisturbed roots performed better.

Barmaley wrote: ↑Sun May 22, 2022 10:04 pm Is it true that tomatoes have one main root stem which can go down up to 4-5' and if it is damaged during transplant the plans still grow side roots and never as deep. The plant with the main root suppose to produce better. If this is true, what about plants made of suckers? Do the develop the main root? Sorry it this theory is wrong - I heard it from a single person and a quick search on the web gave me nothing of value on the subject.

The best way to get a taproot on a tomato plant is to directly sow the seed into the ground. If you plant them in a pot that will cause the roots to spread out. Carolyn Male did not care for growing tomatoes with a taproot. She explained that for the plant to grow and produce the best tomatoes that the roots needed to spread out in the top 8 inches of soil in order to use the most nutrients available. If you trench plant your plants will grow two main root balls which is said to be more beneficial to your plants.

Here is a rather old but very good study on the subject.
http://soilandhealth.org/wp-content/...010137toc.html

Scroll down until you come to the Tomato Chapter.

The tomato tap root is very weak. I don't think it makes much of a difference, but definitely would be best to direct seed if you want intact tap root. In my pots I never notice the tap root, for some reason the middle of the pot is always kind of root free, they just spread around it. If you want a strong tap root, try grafting on solanum torvum, those things have a tap root thick as a finger and go very deep, although I think the overall vigor will be less than the average tomato (less thin roots).

At the end of the season when pulling up the depleted plants I have never really noticed a tap root of any consequence. The root ball becomes extensive and far-reaching with lots of arms/fingers (however they may be described) extending out in all directions. That is how I see things in my gardens.

I have had tap roots but never to the extent mentioned by the OP. They still had finer and more shallow feeder roots. However, most years I hardly ever water. Maybe 3 or 4 times a season, if that, because I think the tomatoes taste better and I am lazy. So I wonder if that encouraged the development of a tap root. I also start from seed. But I also wonder if the tap root helps anchor the plant, makes a stronger plant and one more drought tolerant. It would seem that having both a tap root and abundant shallow feeder roots would be ideal.

Tap roots help with water issues. If your ground dries out, a strong tap root helps to prevent blossom drops and BER.

The feeding layer, as stated already, is only in the first foot of top soil.

As zeuspaul said, tomatoes from cuttings won't develop a taproot, and you need to plant from seeds for that.

I also wanted to add that just because it has a taproot doesn't mean it lacks other kinds of roots (so, it doesn't have to be a one or the other sort of thing). True, you'll probably get more of the other kinds of roots without a taproot, but I don't think this is going to be an advantage, whether or not it's a problem.

If you grow from seed, it'll have a taproot, whether or not that taproot gets its growth interrupted (unless you break it). I mean, even if the taproot doesn't get very long, or if it gets bent, it still exists.

Getting a super long tomato taproot would probably be pretty rare. In my garden, the plants I pull up only have up to about a foot of discernable taproot (usually less), whether they're transplants or vounteers. I say 'discernable' because there may be thinner portions of it that broke off.

Thank you everybody for a lot of interesting facts about the root system. However, the answers bring more questions. And the obvious, of course: do I want my tomatoes have a tap root or not?

I am trying to follow dwarf tomato project and this year I have several dwarf plants to try. I think it may be interesting to start dwarf root project for container growers. If a small ball of roots could collect all needed nutrients from a pot with measured and provided fertilizers so we could use small ports it will be awesome.

@Patti, for some reason I can not open the link.

I think it is pretty unanimous that it is a good thing. It might not be absolutely necessary but I didn't read anything from anyone giving any opinions that it wasn't a good thing, did I miss it?

Barmaley wrote: ↑Mon May 23, 2022 8:55 pm @Patti, for some reason I can not open the link.

For some reason the html link doesn't work. I found a link to the same pdf file.
https://soilandhealth.org/wp-content/up ... 0CROPS.pdf

It is very informative. You need to set aside some time to read it all. Here is part of the summary:

Summary.--Tomato plants are started in especially prepared seed beds, transplanted once or twice, and
then set into the field. The strong taproot, which may develop at the rate of 1 inch per day, is injured and a
dense fibrous root system promoted by transplanting. Plants of the John Baer variety, scarcely 1 month in
the field, reach a depth of 2 feet and a maximum lateral spread of 24 inches. Most of the exceedingly
numerous, much-branched, horizontal laterals occur between 2 and 10 inches in depth. The adventitious
root system develops rapidly but the surface soil is still free from rootlets. A month later when the top has
a transpiring surface of 12 square feet, the roots are very extensive. Many of the strong laterals, all of
which arise in the surface 10 inches of soil, spread horizontally 2 or more feet and, then turning
downward, penetrate into the third and fourth foot of soil. Others pursue a horizontal course throughout,
ending 3 feet or more from the base of the plant. Still others run obliquely downward, usually one strong
root assuming the rôle of a taproot. The main roots often give rise to very long laterals which also
penetrate deeply. All of the roots are extremely well branched, and the 2 feet of soil on all sides of the
plant are well filled with roots to the 3-foot level. The adventitious root system thoroughly ramifies the
surface soil.

The tap root will only tap to the depth of the topsoil layer, at least in my clay. The first layer of subsoil is virtually impenetrable. Most people only have a few inches of topsoil, a little more in raised beds.

All this root talk and I want to experiment now. Previously I've planted long stemmed tomatoes on their side to maximise area of root growth. This was because I planted the seeds very early and keep them out of the ground a long time until weather was better and they had grown rather tall before transplant into the ground. With only about a foot deep of good soil, within the raised beds, and probably a few more inches of topsoil below that laying them down seemed a sensible approach.

This year I haven't done that. But I do want to see if I can get a better plant growth and see by now much.

So, I have two black russians, similar size and adjacent to one another in the beds. Now, how to give one of them additional root space now that they are already planted and established ? Could I hill up the soil around one of them ?

I would focus on the lateral roots. Blend in some of that compost you referred to around the plant up to a meter out if you have the room. And water and mulch (compost) in that meter root zone.

@zeuspaul Great idea, but as you say, only if I have the room. But plants are quite tightly packed in the bed, I think in one metre square I'd be feeding half the tomatoes in the bed and I've only gone and planted like varieties in adjacent positions. Perhaps next year I can do something across beds but I'll have to mix both to ensure soil composition is equivalent I guess before amending/adding too.

You might want to try some bone meal in the root zone you want to encourage.

@zeuspaul yes, I do add blood fish and bone when first planting. If I can get more cover on the zone I want to encourage I will definitely use.