Well, I pot up because of this board.
I started watching this thing a couple of years ago and everyone had a better tomato .... I ended up with close to 900 different seeds :(
So while I try to settle into what is me ( I was previously fully content with my Brandywine), I now find myself with a chunk of stuff to try/carry_on.
So I pot up because these fellas need more room ...

{{gwi:1306705}}

I ( below) am currently about 1/2 way ... 51 different varieties, 602 plants :(

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That is why I try to stay away from here ( but it is hard to do) :)
Why so many? Addiction, sadly admitted.

Rather than re-type it all I hope you don't mind if I just refer you to these previous discussions. ;)

But yes, I do it routinely, primarily for the benefit to the root structure but also because it allows me to start 300+ seedlings in trench trays and plug trays in the same amount of space taken up by 3-4 cell flats.

Dave

Here is a link that might be useful: Why pot-up discussions..

Lots of good reading in the threads Dave mentions. In one of these pot up discussions recently Carolyn pointed to this study done in 1927 concerning root development in vegetable plants including tomatoes. It is one that I go to when I want to read up on the matter.

Here is a link that might be useful: root development study

I pot up 2/3 of my seedlings because I start 3-4 in a half filled pot to save space and then move all but one to new pots. As long as the plants are started in some sort of pot, rather than direct seeded in the garden, the (undesirable) tap root development is inhibited. Changing from a seed cell-pot to a larger pot once also allows you to plant the seedling a little deeper to get a jump on root development from the stem above the root base. If you just go with a seed started in a full, large pot the seedling gets knocked over pretty easily when watering etc. because the root base is at the surface of the soft mix. There is also the problem of surface drying inhibiting root growth for those shallowly rooted young plants.

Interesting. So the idea is that tomatos that aren't transplanted at least once develop tap roots.

I will have to pay more attention to the roots this year as I can't ever recall seeing a tap root on any of the tomatos I have grown.

In the study from the 20s it seems to be comparing direct seeding in the field to potting up at least once. I wonder if it is the potting up that makes the difference or simply being started in a container rather than direct sown?

I will have to have a few sacrifices this year and pot some up while not potting up some others and then yank them and look at the roots.

hoo boy, i just read some more of those past discussions on the topic. Kinda sorry I did :)

didn't realize this is a 'hot topic'.

anyway, I will just 'do it the way i do it' and transplant a few and see what all happens.

I was new at this (starting seeds) so I had no idea where to start. Me and wife had been growing tomatoes outdoors growing on 5 years. I started my seeds in small what looks like peat pots (looks like strings of interlaced twine) and then transplanted into 8oz. styrofoam cups lol...that lasted only about 2 weeks because they grew too fast. Now I have a few of them in 1/2 Gal. milk containers and the rest in plastic folgers coffee cans.

yep, it's those tomato tap roots you have to watch out for

just, everyone completely ignores the fact that no matter what you do
or how you grow them
you will pot them up at least once
you have to
when you plant them out.

.

I pot up because of this board too.

Here is a link that might be useful: this board

i pot up for many reasons, mostof which already mentioned here. i start seeds in a soiless mix, which i buy and mix myself. i costs $$, and i only use what i need to get 3 sets of true leaves. i then transplant to 2.5"(the little square black ones), with organic potting soil, which also costs $$. the plants will live here until i plant them, or give them to someone who does. i like to bury them up to the seed leaves (cotlydons), cuz 'maters will root from the stem if buried. i also use seed trays to save space. i currently use a 6 X 12 greenhouse for seed starting, so space is a premium. i guess i have noticed a taproot while transplanting, but i never break up the root ball when planting in the ground.

So, looking at the threads here it appears most who pot up do so because of 'this board'. No idea what that means.

There also appears to be a study from the 1920s that is mentioned that few have read because it really doesn't advocate potting up at all even though in past threads it was said to.

I dunno, seems like an awful lot of work for no gain.

In the past I have potted up as I started plants too early and had no choice and based upon those results I decided to never start plants so early again. Not really an argument for planting up.

Still looking for a reason to pot up this year.

I understand sowing before the roomy greenhouse conditions allow and needing to conserve space, but for everyone else, why pot up?

My first year growing from seed and they are doing great.
I have potted up twice, from peet pellets to 10 oz cups, and then to 20 oz cups.
Each time I have potted up, I have buried them as deep as possible. I figure at this point, I have quite a lot of stem buried that are now producing roots.
When they go into their final home this week, I will strip off the lower leaves and plant them deep again.
I figure I will have about 7 inches of buried stem by this point. If I hadnt potted up the multiple times, I wouln't have nearly as much rooting stem undergroung if I had just started them in the 20 oz cups, leading to a great root structure.
I'm a noob, but thats my opinion

JAG

Though I haven't done it myself, I've wondered (long before you posted this question) if germinating tomato seeds in a "deep" container, like maybe a 20-inch cup, with only a little soil mix at the bottom, would work. Then instead of re-potting the plant as it grows, keep removing any leaves and adding more soil mix until the container is full to the top. I'd think that would prevent a tap root from growing straight down and would provide the same larger root mass one would get if they were put in a bigger "pot".

The only reason I start mine in small containers is to fit them under the inside lights I use. When I transfer them to something larger immediately after germination, there are daytime temps of 60 and 65 degrees, even though the nights may get down into the low 40s. I rarely have to put my growing seedlings under the lights after that.

I put the young plants outside when it's daytime-warm in a shady spot because they get much better light, even shaded, than under my fluorescents. They slowly harden off as they're exposed to breezes and indirect sunlight for 1-2 weeks. Then I like to put them in a place every day where the shadow gradually shortens so they're eventually fully-exposed to sunlight.

Finally I transplant them into the garden when night-time temps stay in the 50s or higher.

If your tomatoes are doing well in the garden, I wouldn't worry about potting them up or treating them differently (though I know you're just asking why it's done). Let's face it -- the taproot can't grow very much in ANY container we start tomato plants in. Furthermore, after we transplant them more deeply into the garden, the plant will develop a larger root system (with the taproot curled around because of the inadequate container space) regardless of the root mass size when it's transplanted.

Like most techniques for tomato-growing, there's more than one way to skin a cat.

No doubt it's a lot of work but I pot up twice before going to the garden. It's not so much about getting bigger around but getting DEEPER. When I pot up the second time I'll remove some of the lower fuliage and sink them in foot tall containers. When they go to the garden I romove all the foliage except the two branches below the growing point and plant them right up to the lower branches. Now the roots are down there where the moisture is more abundant and consistant. I never get tomato splits and the plants are perky on the hotest summer days and grow to 9'or more. Granted this wouldn't be feasible for the large producer. :-)

Think Spring! I have two snow storms heading my way next week :-(
Tim

The problem with a tap root is that in the garden it keeps going down into cool soil, slowing growth, and it also misses out on the abundant supply of shallow soil nutrients. It is a survival technique for quickly reaching deep soil water in areas with wet and dry seasons. The plant is a vine, so in the wild, adventitious roots from the prostrate stem will aid in getting surface nutrients after the plant has secured its water supply.

Soon after a tap root turns horizontal after hitting an obstruction such as the bottom of a pot it starts putting out lateral roots (=fibrous root system). Same happens when the tip of the tap root is damaged by repotting or simply planting out into the garden from a pot.

ipot up to get more mature plant for short season . 2 ft plants in 8 inch pot can swing like a sword i used clear plastic cups i could see roots . went from 3 or 4 inch to 8 or 9 inch. planted deeper in garden. plants doing very well 1st yr at this practice. ernie

The article from the 20's does not compare directly sown seeds to potted up from my recollection. It does review the effect on root development on potted up vs. non potted up. The roots on the potted up plants looked more substantial and fibrous. The problem is that the results of the testing certainly did not seem to advocate potting up to me. In one experiment, seeds were started in pots. Some of the seedlings were then taken out of those pots and then placed back in the same pots. Later, some of the potted up seedlings were transplanted one more time in the same manner. So, before planting in the field, they had some plants that had not been potted up, others that had been potted up once, and others that had been potted up twice. The appearance of the roots seems to convince people that potting up is a good idea. However, the results of production of the plants convinces me that potting up is not a good idea.

How many of you, when potting up, tranplant into different sized pots? Have you not noticed that the larger the pot, the faster the plant grows? When I pot most transplants into 3 inch pots, and others into 5 inch pots, within a few weeks the ones put into 5 inch pots are consistently 30% larger than the ones that were put into 3 inch pots. The are also in large enough pots that they do not require an additional potting up before set out. In the end, the ones that were potted up once are larger at set out, and took less work. The big caveat is larger pots need more space and are more of a pain for that reason alone. As for results in the garden, my experience is the larger the plant was when it went in the ground, the more production I get (but the main reason for this is in my opinion the fact that I have a short growing season). In terms of leaving the plant in a smaller pot to force root growth, that is certainly possible but nobody that has mentioned this has provided any empirical backup that I recall. Transplanting does appear to result in different root structures, but who cares unless someone can show that these root structures produce more fruit. Ham what you say about tap root might be correct, but what is the difference in fruit production (and were is the evidence to back it up).

justaguy2,

actually the 1927 article does advocate 'potting up' I have clipped the reference and pasted here:

"On plants of the John Baer variety, the taproots were uniformly branched to within 2 inches of the tip. The rate of branching in the first 6 inches was 10 to 12 laterals per inch; at greater depths the number varied from 6 to 8 per inch. At this time the plants were approximately 4 inches tall and had about 4 leaves each. It is clear that such plants could be set into the field only with difficulty. Hence the practice of transplanting one or more times before the plants are finally set into the field. Transplanting or potting of seedlings tends to modify the natural taproot system into a more or less fibrous one, due to the injury to the taproot. The change in the root system is really very profound (Fig. 70)"

Milwaukeeboy,

I understand what you are syaing, but the part that confuzzles me is this :
Transplanting or potting of seedlings tends to modify the natural taproot system into a more or less fibrous one.

I have potted up before, but it isn't something I have done for years. I have never experienced It is clear that such plants could be set into the field only with difficulty. .

I don't have any tap root that I have ever noticed so it is either not there or it is already 'damaged' beyond recognition.

I am not arguing one should or should not pot up, just that based upon my own experience there is no advantage to the extra work *for me*. And the study isn't clear to me that it is comparing potted tomatos not potted up, but put in the garden versus potted tomatos potted up 1 or more times before going to the garden.

I do not pot up and have not done so for two years. I use 2 1/4 x 2 1/4 x 3 1/4 deep 6x6 containers. I plant out after 4-5 weeks when the plants are 6-8" tall. When I plant I bury them deep removing the lower leaves. I have had good luck doing them both ways.

I plant my seeds directly into 3.5" pots and keep them there until ready for the garden. In addition to placing some seeds in the center of the pots, I also place some in the corners. The reason for this is that that if the center seeds do not germinate, or produce weaker seedlings than the corner ones, I can easily transplant corner seedlings into center positions (hey, I'm a scientist and I like things centered!).

For some reason the corner positions tend to germinate faster than center positions (??) so I wind up transplanting about a third of the seedlings each year. Having done this for many years, I have never noticed any differences in the plants or root balls, but then I really haven't kept track of which ones were transplanted. This year I will mark the pots containing transplants and look for differences when putting them out.

My seedlings consistently reach garden size (9-12") in only five weeks and the soil balls are dense with roots.

TomNJ

I went from my egg carton to 8 oz cups last year and my plants were leggy. This year I 'potted up' from the egg carton to 8 oz cups then 20 oz cups. I did BECAUSE I read several posts regarding the benefits and it made a big difference in my tomatoes...they have a much stronger stem and more leaves and roots...even my neighbor who is an authority on all things gardening says I have some really good looking tomatoes...he and another neighbor were down this morning so the other neighbor could buy some of my extras--my 'gardening expert' neighbor will not grow heirloom tomatoes--has to be a red hybrid to make his garden!

Peggy