Four things that I think would help make thick stems would be:
1. Plenty of light from the day the seed sprouts and emerges from the soil, either using powerful indoor lighting or outdoors.
2. Putting the seedling outside at least part of the day from the day it sprouts, weather permitting, so it is exposed to the wind and occasional cold. If indoors some say use a fan.
3. Give the plants plenty of room to grow so they can grow wide as well as just tall if they are forced to compete for light, and put them in a big enough pot so they have room for the roots to grow.
4. Some say too much fertilizer will make a plant grow too tall too fast, but I don't know if this is proven.

I saw in nursery seedlings that are short but having thick stems. How they are growing these seedlings?

Grown in greenhouses. Makes all the difference in the world because of the amount of light they get, the air circulation, and the cooler temperatures provided.

But it is possible to duplicate them inside if you are willing to duplicate a greenhouse environment as much as possible - cooler air temps for slower growth, supplemental air circulation with fans, and provide a truly sufficient supplemental lighting system. Many aren't willing to go to the expense or don't have the room.

Dave

Dave, I realize that you are right about them growing too fast so I am trying to slow mine down. Today I have them outside on the porch although it is raing and 52. Is this too cold to have them out? The nursery wher I go said they keep theirs around 55.
Thanks,

52 won't hurt them if they are getting enough light. If not they will still lean and stretch. That's the goal - to balance air temps with sufficient light.

Weather here is only 35 degrees and it's snowing right now so it's heading your way. ;) My toes are freezing but we have transplanting to do. Right now it is 54 in the greenhouse and all the lights are on the plants because of the overcast and the @#$%# layer of snow on top the greenhouse.

Dave

I agree with Dave. I swear I read every single post on this forum and the Starting from Seed forum, and kept my tomato seedlings in the garage (unless it was absolutely freezing). I also had the fan on them quite a bit, far enough way just to make them kind of quiver. My 'seedlings' have super thick stems :) I suppose they are more plants at this point, I really wish it would warm up so I could get them into the ground!!!

I read somewhere that higher night than day temperatures shortens internode distances of many species. This implies that if daytime greenhouse temperatures are normal, say 80o F. and the night time temperature is higher, say 100o F., then the plants will be shorter. More likely they used something like 60o F. day and 80o F. night, but, theoretically, either should work.

If I find the article, I will post scanned images.

Theoretically it would make sense given nighttime grow rates etc. and would love to give it a try.

But the practical application of it in the greenhouse would be budget blowing. The cost of heating the greenhouse at night just to keep it above 45 and the cost of cooling it in the day to keep it below 70 are already 70% of our overhead. If we went for 80 degrees at night and 60 in the day time, per item plant production costs would quadruple. They'd be really expensive short internode plants. ;)

Dave

It would cost a small fortune to keep a greenhouse at 100* all night :)

Yes, it would be impractical in a greenhouse. It might be practical in an artificial light environment with lights on during the night and lights off during day, with air ventilated in from outdoors in zone 4-6.

I have neither greenhouse nor fan, but I do brush my little babies with my fingertips at least twice a day when checking in on them. The brushing helps harden them up and improve stockiness (similar to the movement of air - artificial or otherwise) and then you get the bonus of that lovely, pine-y scent on your hands!

Rain

Does anyone one have data showing thicker stems will make more tomatoes?

I would think you need more roots, not more stems.

dcarch

Could be but not that I know of other then that thicker stems and shorter internodes usually equals healthier plants with a better circulatory system. So I guess one might assume better production. *shrugs*

But thicker stems and shorter internodes usually also means more roots due to the slower top growth growth.

Dave

Maybe this is why my plants are so stocky and healthy looking. I take them inside at night and put them under my lights where the temperature gets up to 82 to 90 degrees, and put them outside during the day as soon as it hits 50 degrees, and for most of the day the temp was between 50 and 65. Now it is getting warmer during the day, sometimes hits the low 80s.

LOL! You guys got the doublesies?

dcarch: Does anyone one...

digdirt: ...due to the slower top growth growth.

LOL Anney - it's Monday...right? ;)

Dave

I was hoping to read something about feeding/fertilizing.
I start my seeds in my own mixtute, consisting of some fine screened
compost/soil + peat moss + pearlite + coffee grind
I do no have any disease, roting, legginess or mold problems. But my seedlings
seem to grow very slowly. I use half the recomended dosage of liquid fertilizer(for seedlings) because I don't want to burn them
or push them too early on.
I think the amount of nutrients thus supplied is low or the roots are not
getting it. So as suggested in another forum/thread I have added some Epson Salt plus calcium(from my medicine cabinet!!).
I think I will increased the fertilizer rate as well.

I'm planning to grow my seedlings in my basement (65-70 F). Would the plants benefit from being kept in the cooler garage at night (52+ nights only)?

The brushing helps harden them up and improve stockiness

Yes, that works and I have done it by brushing with newspaper. There is a theory that brushing the tops increases production of the plant hormone, ethylene. But, ethylene also causes senescence. The plant growth regulator, Florel, simulates ethylene and is labeled for use on tomatoes. For all I know, used at the right rate, Florel might thicken stems, but surely too much will stunt or kill the plant.

then you get the bonus of that lovely, pine-y scent on your hands!

Are you joking? That does not smell piney to me.

inagf6, go ahead and sprout your seedlings in the basement and grow there till they get their first true leaves. If the temperature in your garage is still in the low 50's then move them out there for ten days to 3 weeks with your lights and do your cold treatment. After that put them back in the basement or outside depending on the weather. Ami

So, I have kept my tomato plants upstairs in ~60s and they are tall and kinda thin. They do have the true leaves. If I put them in my basement at ~50s, will they fill out or am I too late?

jengc, what are you using for grow lights? Ami

Fluorescent lights that I use underneath my cabinets. I will be moving them downstairs to my basement that has the same lights, but hanging from the ceiling. I was going to build up a platform so it is right under the lights.

I've seen some very convincing data in the past which showed that tomato seedlings develop into strong plants when grown near 74-84 degrees. The cold-treatment will benefit them after they are strong enough to handle the changes, but I wouldn't germinate seed or attempt to grow young seedlings in 50-60 degree weather.

This is what I do and I have some plants that are 9"-10" tall with multiple leaf sets with 1/4"+ stems growing in 3" pots by the time I plant out.

1.) Sprout using heat mats about a week or two earlier than recommended and grow in my unheated basement (55-60 degrees, but fairly stable). They grow slower there so I need more time, but the growth isn't leggy.
2.) Keep lights as close to the plants as possible and keep lights on for 14 hours.
3.) Add a very small amount of organic fertilizer after about 5 weeks from sprouting.
4.) Occasionally, use a fan to generate a small breeze on them.
5.) Put them out on my protected porch as early as the weather will allow to let them get some wind and indirect sunlight (take them in at night if temps get too low) - this starts the hardening off stage as well. For me, this usually happens about 7-8 weeks after sprouting.

These steps, along with good seedling care practices (not overwatering, etc.) works well for me. Due to the relatively constant strong breezes I get around my garden, I need sizeable tough plants or they won't last a week after planting out. Mine aren't as stocky as some of the hot house grown ones you see at the nurseries, but it's a lot less money than buying all the plants I need (and probably not getting all the varieties I'd want) and hey it works.

These Big Zac, 36 days after sowing seeds, were grown with a negative temperature differential (light temp. - dark temp.).

Maybe some of the ones you've seen are actually stems taken from adult plants...

Somewhere above: ''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.''

It seems to imply 24 hours a day. Is that correct?

"struwwelpeter(5)

March 22, 2010 at 12:24PM

I read somewhere that higher night than day temperatures shortens internode distances of many species. This implies that if daytime greenhouse temperatures are normal, say 80o F. and the night time temperature is higher, say 100o F., then the plants will be shorter. More likely they used something like 60o F. day and 80o F. night, but, theoretically, either should work."

While I am able to do this method here in Dubai because we still use air-conditioners almost all day and most nights around seed-planting time, I planted seeds late this season because I was traveling. I could bring the seedlings in during the day then leave them out in the hotter temps at night.

I will try this method next season.