How to grow seedlings with thick stems?

briergardener_gwMarch 21, 2010

I am growing my seedlings under the lamp and they looks good, but they don't have thick stems.

I saw in nursery seedlings that are short but having thick stems.

How they are growing these seedlings?

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californian

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.

    Bookmark   March 21, 2010 at 11:03AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

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

    Bookmark   March 21, 2010 at 11:32AM
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joytwo1839(z6 TN)

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,

    Bookmark   March 21, 2010 at 1:53PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

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

    Bookmark   March 21, 2010 at 2:46PM
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armymomma(CenTX 8)

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!!!

    Bookmark   March 21, 2010 at 5:57PM
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miesenbacher(7)

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

1 Like    Bookmark   March 22, 2010 at 3:06AM
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struwwelpeter(5)

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.

    Bookmark   March 22, 2010 at 12:24PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

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

    Bookmark   March 22, 2010 at 3:28PM
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timmy1(6a ri)

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

    Bookmark   March 22, 2010 at 4:40PM
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struwwelpeter(5)

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.

    Bookmark   March 22, 2010 at 5:33PM
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blameitontherain(8 PNW wetandwetta)

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

    Bookmark   March 22, 2010 at 6:03PM
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dcarch7

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

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

dcarch

    Bookmark   March 22, 2010 at 7:00PM
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californian

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.

    Bookmark   March 22, 2010 at 8:01PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

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

    Bookmark   March 22, 2010 at 8:01PM
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anney(Georgia 8)

LOL! You guys got the doublesies?

dcarch: Does anyone one...

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

    Bookmark   March 22, 2010 at 8:18PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

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

Dave

    Bookmark   March 22, 2010 at 9:00PM
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cyrus_gardner(8)

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.

    Bookmark   March 23, 2010 at 2:11AM
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inagf6(5B)

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)?

    Bookmark   March 23, 2010 at 5:55AM
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struwwelpeter(5)

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.

    Bookmark   March 23, 2010 at 10:58AM
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miesenbacher(7)

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

    Bookmark   March 23, 2010 at 2:41PM
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jengc(7)

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?

    Bookmark   April 2, 2010 at 10:59AM
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miesenbacher(7)

jengc, what are you using for grow lights? Ami

    Bookmark   April 2, 2010 at 11:16AM
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jengc(7)

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.

    Bookmark   April 2, 2010 at 12:00PM
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chefrobert

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.

    Bookmark   April 8, 2010 at 11:21AM
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homegardenpa

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.

    Bookmark   April 8, 2010 at 2:36PM
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struwwelpeter(5)

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

Details are here.

    Bookmark   May 9, 2010 at 2:29PM
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