Cold treatment for seedlings

gunrunner · January 12, 2016

https://mountainplover.files.wordpre...-treatment.pdf

I know this has been discussed here before, but I would like to know, if you do this, do you
transplant your seedlings into seperate containers before the cold treatment, or do you wait until the process is complete before transplanting?

Thanks
Mike

Worth1 · January 12, 2016

Mine go into their own containers but even when babies they dont stay warm at night.

Worth

jmsieglaff · January 12, 2016

I transplant before. I transplant at 2-3 sets of true leaves, usually they go back under the lights for another week or so (in the basement which is upper 50s around 60F) then out into the cold frame--where they will experience 40s for certain, sometimes even upper 30s if we have a cold, cloudy 2-3 days in a row.

sjamesNorway · January 13, 2016

The following was first posted by amideutch in 2010, and is what I follow:

Giving Seedlings the Cold Treatment Ever wondered how commercial seedling providers get these beautiful, stalky, plants with thick stems to market? It's called the cold treatment and has been going on at commercial greenhouses for over 30 years. Here's how they do it.

This was taken out of the book "Greenhouse Tomatoes, Lettuce & Cucumbers" by S.H. Wittwer & S. Honma where they recommend 'Cold Treatment' for hardening off tomato seedlings.
The cold treatment should be started just as the first true leaves emerge, whether the seedlings are still in seed rows or pricked-off. Air and soil temperatures should be lowered to 52 to 56 deg F for ten days to three weeks. A ten to twelve day cold treatment is adequate during periods of good sunlight. Three weeks are usually necessary in the fall and early winter when most of the days are cloudy and plant growth is slow. The amount of cold during the ten-day to three week period is more important than the time of day in which it is given. Cold exposure during either the day or night, or both, is effective. Night temperatures of 52 to 56 deg F are recommended when the days are sunny and partly cloudy.
Following the cold treatment, night temperatures should be raised to 58 to 62 deg F. Cool daytime temperatures (60 to 62 deg F) should be maintained in cloudy dull weather. On bright sunny or partly cloudy days, temperatures of 65 to 75 deg F accompanied by good ventilation are suggested.
Tomato plants properly exposed to a cold treatment develop large cotyledons and thick stems, with fewer leaves formed before the first flower cluster, up to double the number of flowers in the first, and often the second clusters, and higher early and total yields.

Basically this cold treatment is used to give healthier, more stalky seedlings that will give increased yields and earlier harvests. In regards to light intensity and duration they had this to say.
The tomato is a facultative short day plant which flowers and fruits earliest if the day is not extended beyond 12 hours by artificial light. Young tomato plants do not need the light intensities of full sunlight. Where there is no overlapping of leaves, light saturation is reached at intensities from 2000 to 3000 foot candles, or about one-fifth to one-third the intensity of direct sunlight at high noon. If artificial lights are used, an intensity of at least 500 foot candles should be provided at the leaf surface. Tests with fluorescent fixtures reveal that Wide Spectrum Gro Lux is slightly superior to cool white.
Hope this helps. Ami

Steve

BigVanVader · January 13, 2016

I follow Craig's method and harden them when still planted densely at the first true leaves stage. They seem to take colder temps well when planted so close.

Fusion_power · January 14, 2016

There is quite a bit of documentation about cold treatment of seedlings and the effect it has on vigor and production. There is very little information about drought stressing tomatoes which is also an effective way to increase production. One of the little tweaks of drought stressing plants is that it postpones flowering by a few days to a couple of weeks. This time is spent in the juvenile growth phase which means the plant becomes much larger before setting fruit. Drought stressed plants have much larger root systems than plants that have not been stressed and have significantly larger total production. Combining cold treatment with drought stress produces a plant that spends longer in the juvenile phase, but sets an early flower cluster that makes a good crop of early tomatoes and continues to produce heavily longer into the summer. I get my best crop of tomatoes from plants that have been both drought and cold stressed.

Another crucial piece of information for a greenhouse seedling grower is that overnight temps between 35 and 45 degrees significantly impacts the plants ability to translocate nutrients through the stem. A few days at these temperatures can permanently stunt a tomato plant..... unless you know that increasing greenhouse temperature to 95 to 100 degrees for several hours the next day totally reverses the effect of an overnight chill. I routinely let my greenhouse fluctuate between 39 degrees and 120 degrees in early spring because the resulting seedlings will take just about any temperature extreme and thrive.

KarenO · January 14, 2016

there is a big difference between cool and cold. 56 degrees to me is just a normal spring night temperature and not cold at all. Greenhouse growers are just trying to approximate normal outdoor conditions by allowing temperature to decrease to 52-56 degrees in their otherwise warm greenhouses. To take that to mean you can nearly freeze your tomato seedlings and that will make them "stronger" is not true. It will check their growth and slow them down in a detrimental way. Ideal seedling growth should be steady and rapid. If they are outgrowing their seedling spaces too quickly, you planted them too early.
Near freezing temperatures may be survivable for tomatoes but will not benefit any tropical plant seedling. Cool and cold are not the same thing and colder is not better.
KarenO

January 15, 2016

Commercial growers use chemicals to keep their young plants stocky. I once was a grower in a small nursery but I can't recall the name of the spray we used.

Worth1 · January 15, 2016

Quote:

Originally Posted by KarenO

there is a big difference between cool and cold. 56 degrees to me is just a normal spring night temperature and not cold at all. Greenhouse growers are just trying to approximate normal outdoor conditions by allowing temperature to decrease to 52-56 degrees in their otherwise warm greenhouses. To take that to mean you can nearly freeze your tomato seedlings and that will make them "stronger" is not true. It will check their growth and slow them down in a detrimental way. Ideal seedling growth should be steady and rapid. If they are outgrowing their seedling spaces too quickly, you planted them too early.
Near freezing temperatures may be survivable for tomatoes but will not benefit any tropical plant seedling. Cool and cold are not the same thing and colder is not better.
KarenO

It is a huge benefit to have as big a plants as you can get when you plant out down here.
Stunting them does no good but when it starts getting warn and staying warm it happens in a hurry.
The soil can go from cool to warm and back to cool.
This year I have very cold sensitive yard plants that still haven't been bit back but it still might happen.
I am starting to see more years this happens here than not.
I had to pull up volunteer green bean plants out of the onion beds to plant onions.
They were flowering and I got stung by a honey bee in the house yesterday.

They way I look at it if it is too cold for me to be outside in flip flops tee shirt and shorts it is too cold for the plants.
That is below 50 most of the time.
Flip flops go off and shoes come on when it gets to freezing maybe.
The cold doesn't seem to bother the wild peppers at all.
They either dont freeze the leaves freeze parts of the stem freeze or they freeze back to the ground.
What ever happens as soon as it warms up they are back into full growth again.

I have no idea how that one Orange Russian seedling made it through a whole winter and turn into a huge plant did it.
I had some seedlings do it in the raised beds too.

I think it is because it doesn't get cold and stay cold for days on end.
And when I say cold I mean almost freezing.

Worth

Johnniemar · January 16, 2016

Started my pepper seeds today. A little early maybe but they grow slowly.

Worth1 · January 16, 2016

Quote:

Originally Posted by Johnniemar

Started my pepper seeds today. A little early maybe but they grow slowly.

Peppers are very forgiving.

The one I have in a container growing was a wee dried up stick I pulled from the yard this winter.

Worth

January 16, 2016

Over the years I haven't had a lot of success with peppers (many varieties) and recently I am reading a lot about peppers producing better in containers--I think this year I am going to try growing them in containers- maybe 2 gallons, and sink the pots in the ground for stability and to keep the rootballs from extreme heat. Any opinions of the idea?

Worth1 · January 16, 2016

Quote:

Originally Posted by JoParrott

Over the years I haven't had a lot of success with peppers (many varieties) and recently I am reading a lot about peppers producing better in containers--I think this year I am going to try growing them in containers- maybe 2 gallons, and sink the pots in the ground for stability and to keep the rootballs from extreme heat. Any opinions of the idea?

My idea about this is it depends on the soil and where you live.

I just about bet you would do great with that MG natures care raised bed soil mixed with perlite and a goodly amount of Plant Tone in a container.

Worth

Johnniemar · January 16, 2016

I planted poblano, bananna, sweet peppers, cayenne, and anaheim. Last year they did great. Put in my beds and mixed a little garden tone around them and a little bit of coffee grounds. Used leaves as mulch.

January 16, 2016

My gardens are all raised beds and I amend the soil constantly- tomatoes, cucumbers, beans, etc all do very well.

January 12, 2016	#1
gunrunner Tomatovillian™ Join Date: Nov 2014 Location: memphis tn Posts: 81	Cold treatment for seedlings https://mountainplover.files.wordpre...-treatment.pdf I know this has been discussed here before, but I would like to know, if you do this, do you transplant your seedlings into seperate containers before the cold treatment, or do you wait until the process is complete before transplanting? Thanks Mike

January 12, 2016	#2
Worth1 Tomatovillian™ Join Date: Feb 2006 Location: Den of Drunken Fools Posts: 38,539	Mine go into their own containers but even when babies they dont stay warm at night. Worth

January 12, 2016	#3
jmsieglaff Tomatovillian™ Join Date: Jan 2014 Location: Southern WI Posts: 2,742	I transplant before. I transplant at 2-3 sets of true leaves, usually they go back under the lights for another week or so (in the basement which is upper 50s around 60F) then out into the cold frame--where they will experience 40s for certain, sometimes even upper 30s if we have a cold, cloudy 2-3 days in a row.

January 13, 2016	#4
sjamesNorway Tomatovillian™ Join Date: Oct 2014 Location: Norway Posts: 1,049	The following was first posted by amideutch in 2010, and is what I follow: Giving Seedlings the Cold Treatment Ever wondered how commercial seedling providers get these beautiful, stalky, plants with thick stems to market? It's called the cold treatment and has been going on at commercial greenhouses for over 30 years. Here's how they do it. This was taken out of the book "Greenhouse Tomatoes, Lettuce & Cucumbers" by S.H. Wittwer & S. Honma where they recommend 'Cold Treatment' for hardening off tomato seedlings. The cold treatment should be started just as the first true leaves emerge, whether the seedlings are still in seed rows or pricked-off. Air and soil temperatures should be lowered to 52 to 56 deg F for ten days to three weeks. A ten to twelve day cold treatment is adequate during periods of good sunlight. Three weeks are usually necessary in the fall and early winter when most of the days are cloudy and plant growth is slow. The amount of cold during the ten-day to three week period is more important than the time of day in which it is given. Cold exposure during either the day or night, or both, is effective. Night temperatures of 52 to 56 deg F are recommended when the days are sunny and partly cloudy. Following the cold treatment, night temperatures should be raised to 58 to 62 deg F. Cool daytime temperatures (60 to 62 deg F) should be maintained in cloudy dull weather. On bright sunny or partly cloudy days, temperatures of 65 to 75 deg F accompanied by good ventilation are suggested. Tomato plants properly exposed to a cold treatment develop large cotyledons and thick stems, with fewer leaves formed before the first flower cluster, up to double the number of flowers in the first, and often the second clusters, and higher early and total yields. Basically this cold treatment is used to give healthier, more stalky seedlings that will give increased yields and earlier harvests. In regards to light intensity and duration they had this to say. The tomato is a facultative short day plant which flowers and fruits earliest if the day is not extended beyond 12 hours by artificial light. Young tomato plants do not need the light intensities of full sunlight. Where there is no overlapping of leaves, light saturation is reached at intensities from 2000 to 3000 foot candles, or about one-fifth to one-third the intensity of direct sunlight at high noon. If artificial lights are used, an intensity of at least 500 foot candles should be provided at the leaf surface. Tests with fluorescent fixtures reveal that Wide Spectrum Gro Lux is slightly superior to cool white. Hope this helps. Ami Steve

January 13, 2016	#5
BigVanVader Tomatovillian™ Join Date: Mar 2014 Location: Greenville, South Carolina Posts: 3,099	I follow Craig's method and harden them when still planted densely at the first true leaves stage. They seem to take colder temps well when planted so close.

January 14, 2016	#6
Fusion_power Tomatovillian™ Join Date: Feb 2006 Location: Alabama Posts: 2,250	There is quite a bit of documentation about cold treatment of seedlings and the effect it has on vigor and production. There is very little information about drought stressing tomatoes which is also an effective way to increase production. One of the little tweaks of drought stressing plants is that it postpones flowering by a few days to a couple of weeks. This time is spent in the juvenile growth phase which means the plant becomes much larger before setting fruit. Drought stressed plants have much larger root systems than plants that have not been stressed and have significantly larger total production. Combining cold treatment with drought stress produces a plant that spends longer in the juvenile phase, but sets an early flower cluster that makes a good crop of early tomatoes and continues to produce heavily longer into the summer. I get my best crop of tomatoes from plants that have been both drought and cold stressed. Another crucial piece of information for a greenhouse seedling grower is that overnight temps between 35 and 45 degrees significantly impacts the plants ability to translocate nutrients through the stem. A few days at these temperatures can permanently stunt a tomato plant..... unless you know that increasing greenhouse temperature to 95 to 100 degrees for several hours the next day totally reverses the effect of an overnight chill. I routinely let my greenhouse fluctuate between 39 degrees and 120 degrees in early spring because the resulting seedlings will take just about any temperature extreme and thrive.

January 14, 2016	#7
KarenO Tomatovillian™ Join Date: Oct 2012 Location: Vancouver Island Posts: 5,931	there is a big difference between cool and cold. 56 degrees to me is just a normal spring night temperature and not cold at all. Greenhouse growers are just trying to approximate normal outdoor conditions by allowing temperature to decrease to 52-56 degrees in their otherwise warm greenhouses. To take that to mean you can nearly freeze your tomato seedlings and that will make them "stronger" is not true. It will check their growth and slow them down in a detrimental way. Ideal seedling growth should be steady and rapid. If they are outgrowing their seedling spaces too quickly, you planted them too early. Near freezing temperatures may be survivable for tomatoes but will not benefit any tropical plant seedling. Cool and cold are not the same thing and colder is not better. KarenO

January 15, 2016	#8
JoParrott Guest Posts: n/a	Commercial growers use chemicals to keep their young plants stocky. I once was a grower in a small nursery but I can't recall the name of the spray we used.

January 16, 2016	#10
Johnniemar Tomatovillian™ Join Date: Jul 2015 Location: North carolina Posts: 199	Started my pepper seeds today. A little early maybe but they grow slowly.