Gardenrod, could you please elaborate little bit on "Now I know why" on ...exposed to cooler temperatures produces better seedling in tomatoes and early cooler temperatures for pepper seedlings may reduce the quality of the outdoor planting Your experience on these two Now I know why are very interesting topics for newbies. -Chandra

Welcome, gardenrod! As you know, this is an amazing group. Just when I think I know "enough", someone comes along with more must-know info.

Cold treatment is a good one to know. I've always done it to some extent but, after the recent discussion on it and further reading, I'm going to really push it this year. Too bad peppers don't appreciate it.

Diane

Chandra,
I suspect gardenrod is referring to the discussion in the Building a Better Tomato Trap thread. Here's a link. Within that post I provided a google search so you, too, can read some of the source documents for details on how to do it.

I hope that helps.

Welcome Gardenrod, and thanks for chiming in!

Seedmama

Here is a link that might be useful: Building a Better Tomato Trap

Chandra-
I will use the cold treatment method on tomatoes for the first time this year- I was just stating what I had picked up from the forum. Dawn and Soonergrandmom have both posted good information on tomatoes and peppers (see Sweet Peppers posting, etc).
I think they should start a posting for temperature impact during seeding activities.

I do not know the rules regarding the copying of other members posts, but here is a detailed description in the Garden Web " How to grow seedlings with thick stems? " posting by "miesenbacher" :

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

Another topic that I have benefited from is the use of a fan to brush tomato seedlings. I had always used the "wave your hand" method, but I will be using a fan this year.
Z

Welcome Gardenrod -
You are absolutely correct and it's funny you should mention the 2 things I'm going to try different this year. I'm not a "newbie" - I've been gardening for 50+ years but I have spindly tomato plants and peppers that are gorgeous but don't make till fall. Dawn told me about the peppers last summer when I was puzzled why such beautiful plants that produced very little till Fall - thinking back I knew I treated the peppers like tomatoes and probably put them out too early. Also, years ago I raised my tomatoes in coldframes and had shorter, thick, healthy plants that transplanted easily - since I started using the greenhouse, heatmats, and florescent lights my plants are spindly and not so healthy looking. "lightbulb here!" I'm going to start on heatmats, then try the cold treatment this year.
I do use fans in the greenhouse - they are on timers, and I know the air circulation helps with healthier plants for many reasons.
We never get too old or too smart to learn something new. I appreciate all the people who share their views here.

Gardenrod,

All of us are still learning. I say often that I learn something new here every single day and it is so very true. As Diane said, we have an amazing group of people here. My attitiude is that we are much stronger/better prepared for anything as a group than any one of us ever could be alone. Besides that, who else understands our gardening obsession better than other folks similarly afflicted?

Diane, I've always done the cold treatment too, but not really as part of a deliberate plan. Rather, my tiny tomato seedlings get the cold treatment when they are kicked off the lighted seedstarting shelf and moved out to the back porch to make room for other seeds I need to start.

Before I started moving the plants out to the porch while they were very small, they got big and lush indoors but didn't adapt as easily once they were moved outdoors to harden off. Clearly, they'd had it easy for too long. Now that they are exposed to cooler temps earlier, they seem tougher and hardier even though not as tall and lush.

Maybe this year I'll proceed with a plan and move them out when they "should be" put out for cold treatment instead of just haphazardly doing it when the plant shelf is too full and I have the urge to grow more seeds.

Chandra, As others so aptly pointed out, a certain amount of exposure at a young age benefits tomatoes in ways that we may not fully understand. Plants exposed to cold treatment at a certain stage seem to produce more heavily and to perform better later on.

By contrast, peppers (and I think from my observations this applies a bit more to hot peppers than to sweet peppers) that are exposed to cooler temps earlier in the year can remain stunted for a long time and unproductive for the entire season.

I used to transplant peppers out into the ground at about the same time I transplanted tomatoes. I struggled for years to make sense of why my pepper plants looked fine and grew well but didn't produce heavily until fall. The tomatoes were producing just fine, so I knew there was something I didn't know and didn't understand about the conditions pepper plants needed for optimal performance.

After learning about the pepper plant/temperature connection, I started holding my pepper plants inside longer and waiting to transplant them out a couple of weeks later than the tomato plants. The difference in yield was impressive. Now it is just a part of my routine.

I haven't done objective testing with a control group, but I'd say that by holding the pepper plants inside longer and planting them only after the weather/soil are at the temps they like, I am harvesting twice as much as before, and I am harvesting 4 to 6 weeks earlier than before.

Last year, the pepper harvest began in earnest so early that it surprised even me. My plants went into the ground in early May, and I was harvesting sweet peppers and jalapenos in mid-June. It probably did help the hot peppers somewhat that we were hot earlier in the season than usual since they thrive on heat. I just pulled out my harvest record book from last year and I harvested 10 lbs. 2 oz. of jalapeno peppers on June 15th. That is the largest early harvest of hot peppers that I've ever had. If I was not already convinced that planting peppers late was a useful technique, last year's June harvest convinced me.

I use two fans for circulation in the guest room where I keep my seed starting shelf. The ceiling fan stays on 24/7 and then I have an oscillating fan I use to toughen up plants. The light movement of the circulating air helps the plants develop stronger, stockier stems. You know, the same thing is true of trees. Young trees that are tightly staked so they cannot bend much in the wind are weaker over their lifetime than trees that were not tightly staked or that were not staked at all. With the trees, the early exposure to real wind helps build stronger wood. By exposing our tomato plants to circulating air while they are inside, we are preparing them better for the stronger winds they'll be exposed to outdoors.

As for the effect of soil temperatures on germination of seeds, the most reliable data I've ever seen is that on Tom Clothier's website. I'll find it and link it. Using his chart, you can see exactly which temperatures give the best germination rates. However, most of us have to start seeds of some types a bit earlier than the optimum temperature on his charts because we're in a constant race to "make" our garden grow and produce before the high summer heat shuts it down. Carrots, for example, sprout quickly in very warm to hot soil, but grow poorly in it. So, we have to settle for lower germination rates and slower germination times so that our carrots can grow during the time when soil and air temperatures are optimal for them.

Finally, much of what I know/understand about soil and air temperatures and their effect on vegetable plant growth and production I learned from Dr. Cotner's book. Before his book came out, I understood that some crops go into the ground earlier and some later but didn't truly understand exactly how temperatures affect growth and performance. I still have to refer to his book to doublecheck the temperatures various veggies need, but at least now I know enough to check the book for his recommendations instead of blindly following the calendar, or just "guessing" that a particular vegetable can go into the ground at a certain time.

Dawn

Here is a link that might be useful: Effect of Temperature on Seed Germination

very very interesting to read all your points on effetco of temperatures on germination, seedling health and production. I never thought about these things, I guess gardeners around the equator may not deals these things? as they experiencing almost equilibrium temperature through out the year. When I was working at CGIAR/UN center at Colombo (Sri Lanka), I asked one question 'when winter start here' to my Sri Lankan friend , he started laughing at my question. later I realized that there is no seasonality in the that part of the world...its always summer!!! raining all over that year, vegetation is always green... how lucky they are? no need cold frames, greenhouse, winter sowing, no worry about frost, hard freeze like whet we experience here... But one thing for sure, we need all seasons, else its kind of monotonous life for 365ays... not much diversity in vegetables, flowers, what we experience here even for short time.

biradarcm-
I lived in Singapore and Kuala Lumpur for about 5 years (Singapore is just 60 miles from the Equator) and tried to grow tomatoes every year. I was able to eat a few, but with the constant high temperature, they just don't mature the way they do here. The people there seem to eat tomatoes with a lot of green in them.
I also grew tomatoes in the window of my office in Washington, D.C., and actually harvested a few there.
Its nice to be back in Oklahoma where all I have to worry about are pests, frosts, hail, huge temperature shifts and tornadoes.
Z

Gardenrod,

You forgot to mention duststorms, thundersnow, dereco winds, flash flooding, ice storms, wildfire and earthquakes. Oh, and plagues of grasshoppers.

Other than that, gardening here is a breeze.

Dawn