Transplanting seedlings reduces yields?

TomNJ · November 6, 2011

For many years I have read how transplanting (potting up) causes seedlings to develop a more fibrous root system which is presumed to be beneficial. My own experience does not support this position. I start all my tomato seeds in 3.5" pots and leave them, although about 25% of my seedlings do get transplanted to fill empty center spots in the containers. In over 30 years of doing this I have never noticed any difference between those that were transplanted and those that were not. When I take my plants to the garden they are all the same size, the root balls look the same, and they all perform equally in the garden.

I found an extensive study conducted at the University of Nebraska in 1927 that examines the effects of transplanting.

http://www.sustainablefarmer.com/pdf...evelopment.pdf

The section on tomatoes starts on page 180. The first several pages clearly shows that disturbing the tap root causes a more fibrous root system, however, transplanting also checks plant development. What really matters is the health and yield of the plants when in the field. In this regard the report states on page 192:

"Usually the seedlings are transplanted when they are about 2 inches high and more space given each. In this process the roots are more or less severely pruned and the new root system is much more fibrous. Frequently a second transplanting is made in which each plant is given still more room or transplanted in a suitable receptacle such as a flowerpot, paper band, tin can, etc.

Since the root system is disturbed and the development of the plant more or less checked at each transplanting, it might be concluded that plants grown from seed sown directly in pots or other containers would grow more vigorously and give a higher yield than those once or twice transplanted. In fact this has been shown by numerous investigations to be the case. That transplanting in itself does not promote an early crop nor an increased yield has been also clearly demonstrated.

In an experiment in Wisconsin three crops of tomatoes were grown . . . In each case seeds were planted singly in 6-inch pots in the greenhouse; when the plants were about 2 inches in height, two-thirds of the whole number were dug up and reset in the same pots; later, one-half of these were again transplanted in a similar manner. As soon as weather permitted, 10 plants of each lot were knocked from the pots and set 4 by 8 feet apart in open ground, every precaution being taken to avoid injury to the roots. Those not transplanted yielded more than those once transplanted, while those twice transplanted yielded least. The total for 10 plants with each treatment during a 3-year period was, 1,175, 1,131, and 1,001 pounds, respectively.

Does anyone else here have any studies, experiments, or experience that shows transplanting seedlings actually improves plant vigor or yield? Seems like an awful lot of work if no benefits are realized.

TomNJ

tgplp · November 6, 2011

Hey Tom- when you transplant your tomatoes, do you plant them deep in the soil, so roots grow along the stem? That is what gives the tomato a bigger rootball.

I transplant some of my tomato seedlings, and they always grow bigger and better.

Taryn

ddsack · November 6, 2011

No studies here, but for some it is about using our indoor seed starting space efficiently. I grow too many seedlings to have just one per 6" pot in the house while under lights. I have a light stand with 4, 4 foot shop lights on each of two tiers, for a total of 8 lights, and though I have room for one more tier, so far I have not had to use it, and I'm not too crazy about buying more, and running 12 lights. I can still get all the seedlings under the lights after transplanting from mass start cell packs into individual styrafoam cups. But many years I do a second transplant into 4" - 6" nursery pots, and at that point they are outside and come into the garage at night.

There are so many micro-variables after transplanting into the garden that I'm not sure that that a home gardener can always tell why some plants produce better than others. I usually grow two or more plants per variety each season, and it's not at all uncommon for one sibling to be slightly more productive.

It does make sense that undisturbed roots would be happiest to not have their little feeders broken and bruised. But tomatoes root so easily that they seem to bounce back from root stress in a matter of days, if not hours. I grow for taste, not production, so I actually don't need to worry about growing a few more per plant. I aways have more tomatoes than I can use up.
I think you should keep doing what works for you.

TomNJ · November 6, 2011

Quote:

Originally Posted by tgplp

Hey Tom- when you transplant your tomatoes, do you plant them deep in the soil, so roots grow along the stem?
Taryn

Yes, my seedlings are about 12-14" after five weeks under lights, so I remove the lower branches and plant them deep so new roots can develop along the stem.

TomNJ

tgplp · November 6, 2011

Hm, if you plant them deep then roots should grow bigger than if you hadn't transplanted them.

I don't know why you wouldn't get better results...

Taryn

TomNJ · November 6, 2011

Quote:

Originally Posted by tgplp

Hm, if you plant them deep then roots should grow bigger than if you hadn't transplanted them.

I don't know why you wouldn't get better results...

Taryn

Not sure if we are talking about the same transplanting. I was referring to transferring small seedlings into larger pots (potting up), not transplanting finished seedlings into the garden. I agree that planting finished seedlings deep will improve the root system since new roots will grow from the buried stem.

TomNJ

tgplp · November 6, 2011

Sorry I should've been more clear! I too am referring to potting up. Gosh, now I am confused. I just reread what I posted earlier and it is very hard to follow. Sorry!!!

What I meant to say was something like this: I am surprised your seedlings that have been potted up aren't any bigger than the other seedlings. Lol!

Taryn

Wi-sunflower · November 7, 2011

I think I would discount much of that study due to the fact that it was done so long ago (1927). Back then the knowledge of fertilizer and other nutrients wasn't what it is today. Not to mention there wasn't much of any of the stuff we have now available then.

Another thing is the Wisconsin connection. From my own experience with the UW extension system when I was involved with starting the Wi Fresh Vegetable Grower Assoc, most of the Wi research is designed strictly for the canning companies. Just something to take into account.

Carol

ScottinAtlanta · November 7, 2011

I have a question about potting up - do you plant deep at that point as well?

TomNJ · November 7, 2011

Quote:

Originally Posted by tgplp

I am surprised your seedlings that have been potted up aren't any bigger than the other seedlings.

Taryn

I typically grow 36 tomato plants (6-8 varieties) in two 1020 trays, each holding 18 x 3.5"square plastic pots. If I have enough seeds, I sow 2-3 seeds in the center of each pot, and another 2-3 in corners as transplant spares (much easier to extract seedlings from a corner position using a curved grapefruit knife). Inevitably some center positions are empty, late or weak, and in these cases I transplant healthy corner plants into the center, burying them a little deeper. On average about 75% of the seedlings are undisturbed and about 25% are transplanted, which is a lot less work than transplanting 100%, or worse yet potting up a second time.

At plant out time the plants are pretty much identical within a variety and the root balls look the same as well. I've just never seen any consistent difference.

While the 1927 study is old, I don't think the principles of tomato growth have changed. In the Wisconsin experiment the seedlings, undisturbed and transplanted, were in the same 6" pot, which eliminates soil, fertilizer, light, and temperature as variables.

TomNJ

TomNJ · November 7, 2011

Quote:

Originally Posted by ScottinAtlanta

I have a question about potting up - do you plant deep at that point as well?

I do but only a little, burying about a quarter to half of the stem but not up to the lower leaves as most people do. I want the seedlings to be similar in height so they get the same amount of light from the fluorescent tubes.

TomNJ

**carolyn137** · November 7, 2011

You asked about another source and here's another one, also from the 20's when it was the the thing to do, that is, to study the basic traits of growth, pollination, etc.

I don't know if this one is the same as what you linked to above b'c that one won't load for me but it may well be since this one is also 1927 and done in Nebraska.

http://www.soilandhealth.org/01aglib...010137toc.html

Just scroll down to the chapter on Tomatoes.

I've been posting that link for about 20 years online and different folks have interpreted the results differently.

It does show that direct seeding with no transplanting leads to a tap root system, which I and some others feel is not as good as a fibrous root system, since the latter has much more root surface area for uptake of water and nutrients and oxygen.

Transplanting just once converts the tap root structure to a fibrous structure and that's all I ever do, is transplant once from the seed pans or professional 20 row inserts.

I transplant to inserts with about 2 inch plastic cells, 4 to one pack, 8 paks to the insert, so 32 plants and they're grown on from there to outside transplant size of about 6- 9 imches.

The more you pot up the larger the root system is and it's very fragile, so you get a lot of breakage.

Are my plants rootbound? Yes, and that's what I want them to be so that when planted they take off ASAP and have always grown well.

I adopted some of my methods from a close friend who is a commercial grower and I would sow seeds at home, drive the nursery trays to his place, put them in the seed house, and when 1-2 inches tall transplant them as I mentioned above.

A tap root system may be OK for those who have little rain or not enough irrigation, but other than that I can't see working with direct seeded tap root plants. Another consideration is growing plants outside vs those that are grown inside as in hydroponic growing, etc,

It is done in CA, one place I know, by large scale commercial tomato growers and then they hit them with lots of foliar fertilizer and abundant irrigation.

I must say that I'm a bit surprised that you never saw a difference in direct seeded, left alone plants, vs transplanting at least once.

Have you ever grown a single variety at one time and grown them both ways so as to have at least one control and lessen the variables?

November 7, 2011

I was curious about the same thing so I planted some seed last fall to see if up potted or non up potted plants performed best. I didn't want to up pot if it didn't improve the plants. I planted the same variety seed in three cell packs with nine cells per pack. All growing conditions were the same. After about three weeks, I up potted one cell pack to 3" square containers. I removed the seedlings from one cell pack and then replanted the seedlings back into the same cells. The third cell pack was allowed to grow undisturbed. The seedlings replanted into the same cells grew faster than the undisturbed seedlings. The seedlings in the 3" pots grew faster than the other two. For me, disturbing the tap root and the addition of extra soil improved the growth rate of the plants. The transplanted plants also developed thicker stems. After about eight weeks, the undisturbed plants were tall but spindly on thin stems. The transplanted seedlings were taller with thicker stems and heavier foliage.

I also messed around a little with another cell pack to determine how much physical abuse tiny seedlings could take in the up potting process without harming the seedlings. I found the seedlings could absorb a lot of punishment when pulling them from the germinating medium for up potting. I could hear the tiny hair roots tearing as I pulled them, but they lived and grew fine after transplanting them.

Ted

TomNJ · November 7, 2011

Yes Carolyn the article I linked to is the same one you listed. I have done side by side comparisons with the same variety and did not see any difference in the seedlings at plant out time.

I can see how potting up to a larger pot with more soil can improve the seedling growth, but what I am looking at is effect of transplanting alone. The question is whether there is any benefit from starting in small pots and transplanting up to larger pots versus starting in the larger pots to begin with and leaving them there. The 1927 study clearly states that potting up does not increase yield, which is all I am concerned about. Yield is a bit more difficult for me to compare as more variables are involved once the plants are set out in the field.

TomNJ

travis · November 8, 2011

For maximum yield in numbers of fruit per plant in perfect market condition, I would refer to greenhouse operations for guidance.

Think about it. A tomato vine is genetically predisposed to a certain number of blossoms clusters per shoot with a certain number of blossoms per cluster. If the goal is to achieve one fruit per blossom, then the ideal environment for achieving that goal can only be created inside a hothouse.

Therefore, I would refer to highly refined hothouse cultural practices to learn how to maximize yield of perfect fruit per vine.

November 6, 2011	#1
TomNJ Tomatovillian™ Join Date: May 2009 Location: Floyd VA Posts: 771	Transplanting seedlings reduces yields? For many years I have read how transplanting (potting up) causes seedlings to develop a more fibrous root system which is presumed to be beneficial. My own experience does not support this position. I start all my tomato seeds in 3.5" pots and leave them, although about 25% of my seedlings do get transplanted to fill empty center spots in the containers. In over 30 years of doing this I have never noticed any difference between those that were transplanted and those that were not. When I take my plants to the garden they are all the same size, the root balls look the same, and they all perform equally in the garden. I found an extensive study conducted at the University of Nebraska in 1927 that examines the effects of transplanting. http://www.sustainablefarmer.com/pdf...evelopment.pdf The section on tomatoes starts on page 180. The first several pages clearly shows that disturbing the tap root causes a more fibrous root system, however, transplanting also checks plant development. What really matters is the health and yield of the plants when in the field. In this regard the report states on page 192: "Usually the seedlings are transplanted when they are about 2 inches high and more space given each. In this process the roots are more or less severely pruned and the new root system is much more fibrous. Frequently a second transplanting is made in which each plant is given still more room or transplanted in a suitable receptacle such as a flowerpot, paper band, tin can, etc. Since the root system is disturbed and the development of the plant more or less checked at each transplanting, it might be concluded that plants grown from seed sown directly in pots or other containers would grow more vigorously and give a higher yield than those once or twice transplanted. In fact this has been shown by numerous investigations to be the case. That transplanting in itself does not promote an early crop nor an increased yield has been also clearly demonstrated. In an experiment in Wisconsin three crops of tomatoes were grown . . . In each case seeds were planted singly in 6-inch pots in the greenhouse; when the plants were about 2 inches in height, two-thirds of the whole number were dug up and reset in the same pots; later, one-half of these were again transplanted in a similar manner. As soon as weather permitted, 10 plants of each lot were knocked from the pots and set 4 by 8 feet apart in open ground, every precaution being taken to avoid injury to the roots. Those not transplanted yielded more than those once transplanted, while those twice transplanted yielded least. The total for 10 plants with each treatment during a 3-year period was, 1,175, 1,131, and 1,001 pounds, respectively. Does anyone else here have any studies, experiments, or experience that shows transplanting seedlings actually improves plant vigor or yield? Seems like an awful lot of work if no benefits are realized. TomNJ

November 6, 2011	#3
ddsack Tomatovillian™ Join Date: Jan 2006 Location: Northern Minnesota - zone 3 Posts: 3,231	No studies here, but for some it is about using our indoor seed starting space efficiently. I grow too many seedlings to have just one per 6" pot in the house while under lights. I have a light stand with 4, 4 foot shop lights on each of two tiers, for a total of 8 lights, and though I have room for one more tier, so far I have not had to use it, and I'm not too crazy about buying more, and running 12 lights. I can still get all the seedlings under the lights after transplanting from mass start cell packs into individual styrafoam cups. But many years I do a second transplant into 4" - 6" nursery pots, and at that point they are outside and come into the garage at night. There are so many micro-variables after transplanting into the garden that I'm not sure that that a home gardener can always tell why some plants produce better than others. I usually grow two or more plants per variety each season, and it's not at all uncommon for one sibling to be slightly more productive. It does make sense that undisturbed roots would be happiest to not have their little feeders broken and bruised. But tomatoes root so easily that they seem to bounce back from root stress in a matter of days, if not hours. I grow for taste, not production, so I actually don't need to worry about growing a few more per plant. I aways have more tomatoes than I can use up. I think you should keep doing what works for you. __________________ Dee **************

November 7, 2011	#12
carolyn137 Moderator Emeritus Join Date: Jan 2006 Location: Upstate NY, zone 4b/5a Posts: 21,169	You asked about another source and here's another one, also from the 20's when it was the the thing to do, that is, to study the basic traits of growth, pollination, etc. I don't know if this one is the same as what you linked to above b'c that one won't load for me but it may well be since this one is also 1927 and done in Nebraska. http://www.soilandhealth.org/01aglib...010137toc.html Just scroll down to the chapter on Tomatoes. I've been posting that link for about 20 years online and different folks have interpreted the results differently. It does show that direct seeding with no transplanting leads to a tap root system, which I and some others feel is not as good as a fibrous root system, since the latter has much more root surface area for uptake of water and nutrients and oxygen. Transplanting just once converts the tap root structure to a fibrous structure and that's all I ever do, is transplant once from the seed pans or professional 20 row inserts. I transplant to inserts with about 2 inch plastic cells, 4 to one pack, 8 paks to the insert, so 32 plants and they're grown on from there to outside transplant size of about 6- 9 imches. The more you pot up the larger the root system is and it's very fragile, so you get a lot of breakage. Are my plants rootbound? Yes, and that's what I want them to be so that when planted they take off ASAP and have always grown well. I adopted some of my methods from a close friend who is a commercial grower and I would sow seeds at home, drive the nursery trays to his place, put them in the seed house, and when 1-2 inches tall transplant them as I mentioned above. A tap root system may be OK for those who have little rain or not enough irrigation, but other than that I can't see working with direct seeded tap root plants. Another consideration is growing plants outside vs those that are grown inside as in hydroponic growing, etc, It is done in CA, one place I know, by large scale commercial tomato growers and then they hit them with lots of foliar fertilizer and abundant irrigation. I must say that I'm a bit surprised that you never saw a difference in direct seeded, left alone plants, vs transplanting at least once. Have you ever grown a single variety at one time and grown them both ways so as to have at least one control and lessen the variables? __________________ Carolyn

November 6, 2011	#2
tgplp Tomatovillian™ Join Date: Jan 2011 Location: Pacific North West, zone 8a Posts: 510	Hey Tom- when you transplant your tomatoes, do you plant them deep in the soil, so roots grow along the stem? That is what gives the tomato a bigger rootball. I transplant some of my tomato seedlings, and they always grow bigger and better. Taryn

November 7, 2011	#8
Wi-sunflower Tomatovillian™ Join Date: Nov 2008 Location: Wisconsin Posts: 2,591	I think I would discount much of that study due to the fact that it was done so long ago (1927). Back then the knowledge of fertilizer and other nutrients wasn't what it is today. Not to mention there wasn't much of any of the stuff we have now available then. Another thing is the Wisconsin connection. From my own experience with the UW extension system when I was involved with starting the Wi Fresh Vegetable Grower Assoc, most of the Wi research is designed strictly for the canning companies. Just something to take into account. Carol

November 7, 2011	#9
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	I have a question about potting up - do you plant deep at that point as well?

November 7, 2011	#13
tedln Guest Posts: n/a	I was curious about the same thing so I planted some seed last fall to see if up potted or non up potted plants performed best. I didn't want to up pot if it didn't improve the plants. I planted the same variety seed in three cell packs with nine cells per pack. All growing conditions were the same. After about three weeks, I up potted one cell pack to 3" square containers. I removed the seedlings from one cell pack and then replanted the seedlings back into the same cells. The third cell pack was allowed to grow undisturbed. The seedlings replanted into the same cells grew faster than the undisturbed seedlings. The seedlings in the 3" pots grew faster than the other two. For me, disturbing the tap root and the addition of extra soil improved the growth rate of the plants. The transplanted plants also developed thicker stems. After about eight weeks, the undisturbed plants were tall but spindly on thin stems. The transplanted seedlings were taller with thicker stems and heavier foliage. I also messed around a little with another cell pack to determine how much physical abuse tiny seedlings could take in the up potting process without harming the seedlings. I found the seedlings could absorb a lot of punishment when pulling them from the germinating medium for up potting. I could hear the tiny hair roots tearing as I pulled them, but they lived and grew fine after transplanting them. Ted

November 8, 2011	#15
travis Tomatovillian™ Join Date: Jan 2006 Location: Evansville, IN Posts: 2,984	For maximum yield in numbers of fruit per plant in perfect market condition, I would refer to greenhouse operations for guidance. Think about it. A tomato vine is genetically predisposed to a certain number of blossoms clusters per shoot with a certain number of blossoms per cluster. If the goal is to achieve one fruit per blossom, then the ideal environment for achieving that goal can only be created inside a hothouse. Therefore, I would refer to highly refined hothouse cultural practices to learn how to maximize yield of perfect fruit per vine.