What am I doing wrong with my tomato seedlings?

LonesomeDuck · May 3, 2019

I have planted my own tomato seeds for the more unique varieties that I can't buy plants for for several years now. Each year, the plants end up being too tall, leggy, and lethargic with some white blotchy spots on the leaves. I end up losing about half of them when transplanting into the ground because they are so weak.

I use miracle gro potting mix and plant the seeds into 3" pots, temperature in the room is about 72 degrees, use a heat pad to help seed germination, and they are under a grow light. In contrast, my pepper seedlings seem to do just fine each year and somehow aren't affected by the same symptoms as the tomato seedlings.

Thoughts on what could be causing these issues?

SeanInVa · May 14, 2019

I think some posters answered on your intro thread but to add to what they posted -

- Are you sowing directly in the MG potting mix? I am having good success doing this (using the moisture control potting soil) - but some people have trouble. You might want to consider a good seed starting mix instead. The Jiffy stuff at the big box stores seems to work well for most people.

- Leggy plants tends to be caused by not enough light. What kind of grow light are you using? How far away from the plants do you keep it?

- As stated on the other thread, a fan blowing a gentle breeze will help the plants grow a thicker, more robust stem. You just want them to wave back and forth a bit, not blow them over.

- White blotchy spots could be light burn. Do you mean bright-white, or more of a light tan? This would seem to suggest the lights are too close or too strong, which if so, is odd that they would be leggy.

- Do you remove the heat pad after seeds germinate?

Cole_Robbie · May 14, 2019

I agree that it sounds like not enough light, or being too far away from the bulb.

Legginess can be corrected by transplanting. Just bury the excess stem, and it will grow roots. When I sell plants in 4" pots, they have already been transplanted twice at that point, from starting mix to 6packs, then to the 4" pots. Each transplanting solves any legginess I have.

ginger2778 · May 14, 2019

Definitely the legginess is from them needing more and closer light. Put them as close tobyour grow light as uou can without burning the leaves. If you can touch the light, and you dont feel heat, then 2" is not too close.

If your room temp. Is 72F, then why are you using a heat mat? Tomato seeds germinate easily at that temp, why risk growing fungus and bacteria with the extra heat?

Miracle gro moisture control retains water, for seedlings that's just an invitation to grow fungus, because its too wet. You are much better off without a moisture control potting mix. Someone mentioned the Jiffy at HD, that would be fine.( I don't like any Scott's product, I have always had poor performance from them. Lately even their seed starting potting mix has given folks a lot If seedling deaths. )

Also put a gentle fan on your seedlings 24/7, this will strengthen the stems from them bending and waving in the breeze.

When the seedlings in those 3" pots get their first set of true leaves, gently lift them Out of the mix and replant them more deeply so more of the stem hairs will become roots, giving you a stronger plant. At the samevtimevyou do this, it's time to add just a pinch of fetilizer, my favorite for this stage is Tomato Maker, the stuff is magical for seedlings. This usvthe stage where youvshould be trying to givevthem natural lightnifvuou can.
After the first 4 weeks go by, time to give them one last pinch of Tomato Maker. This will be the last fertilizer you need until final transplant.

mikemansker · May 14, 2019

I always start seeds indoors in March. Usually, by April, temperatures in southern Missouri are upper 30's low 40's. As soon as I can, I get them into a portable greenhouse with a portable heater. I don't think there is any substitute for natural sunlight.

This is what I use: https://amazon.com/gp/product/B01GDV...?ie=UTF8&psc=1

You get healthy plants (though sometimes they are huge by the time I am able to transplant them.)

Just my experience for what it's worth.

clkeiper · May 15, 2019

are you transplanting directly from the grow light area to the garden? that is a recipe for disaster. they aren't used to that amount of sunlight and that will burn them and kill them.

May 3, 2019	#1
LonesomeDuck Tomatovillian™ Join Date: Jul 2016 Location: Indiana Posts: 2	What am I doing wrong with my tomato seedlings? I have planted my own tomato seeds for the more unique varieties that I can't buy plants for for several years now. Each year, the plants end up being too tall, leggy, and lethargic with some white blotchy spots on the leaves. I end up losing about half of them when transplanting into the ground because they are so weak. I use miracle gro potting mix and plant the seeds into 3" pots, temperature in the room is about 72 degrees, use a heat pad to help seed germination, and they are under a grow light. In contrast, my pepper seedlings seem to do just fine each year and somehow aren't affected by the same symptoms as the tomato seedlings. Thoughts on what could be causing these issues?

May 15, 2019	#6
clkeiper Tomatovillian™ Join Date: Nov 2011 Location: ohio Posts: 4,350	are you transplanting directly from the grow light area to the garden? that is a recipe for disaster. they aren't used to that amount of sunlight and that will burn them and kill them. __________________ carolyn k Last edited by clkeiper; May 15, 2019 at 06:40 PM.

May 14, 2019	#2
SeanInVa Tomatovillian™ Join Date: Feb 2013 Location: Gloucester, Virginia Posts: 90	I think some posters answered on your intro thread but to add to what they posted - - Are you sowing directly in the MG potting mix? I am having good success doing this (using the moisture control potting soil) - but some people have trouble. You might want to consider a good seed starting mix instead. The Jiffy stuff at the big box stores seems to work well for most people. - Leggy plants tends to be caused by not enough light. What kind of grow light are you using? How far away from the plants do you keep it? - As stated on the other thread, a fan blowing a gentle breeze will help the plants grow a thicker, more robust stem. You just want them to wave back and forth a bit, not blow them over. - White blotchy spots could be light burn. Do you mean bright-white, or more of a light tan? This would seem to suggest the lights are too close or too strong, which if so, is odd that they would be leggy. - Do you remove the heat pad after seeds germinate?

May 14, 2019	#3
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	I agree that it sounds like not enough light, or being too far away from the bulb. Legginess can be corrected by transplanting. Just bury the excess stem, and it will grow roots. When I sell plants in 4" pots, they have already been transplanted twice at that point, from starting mix to 6packs, then to the 4" pots. Each transplanting solves any legginess I have.

May 14, 2019	#4
ginger2778 Tomatovillian™ Join Date: Aug 2011 Location: Plantation, Florida zone 10 Posts: 9,283	Definitely the legginess is from them needing more and closer light. Put them as close tobyour grow light as uou can without burning the leaves. If you can touch the light, and you dont feel heat, then 2" is not too close. If your room temp. Is 72F, then why are you using a heat mat? Tomato seeds germinate easily at that temp, why risk growing fungus and bacteria with the extra heat? Miracle gro moisture control retains water, for seedlings that's just an invitation to grow fungus, because its too wet. You are much better off without a moisture control potting mix. Someone mentioned the Jiffy at HD, that would be fine.( I don't like any Scott's product, I have always had poor performance from them. Lately even their seed starting potting mix has given folks a lot If seedling deaths. ) Also put a gentle fan on your seedlings 24/7, this will strengthen the stems from them bending and waving in the breeze. When the seedlings in those 3" pots get their first set of true leaves, gently lift them Out of the mix and replant them more deeply so more of the stem hairs will become roots, giving you a stronger plant. At the samevtimevyou do this, it's time to add just a pinch of fetilizer, my favorite for this stage is Tomato Maker, the stuff is magical for seedlings. This usvthe stage where youvshould be trying to givevthem natural lightnifvuou can. After the first 4 weeks go by, time to give them one last pinch of Tomato Maker. This will be the last fertilizer you need until final transplant.

May 14, 2019	#5
mikemansker Tomatovillian™ Join Date: Feb 2013 Location: Branson MO Posts: 441	I always start seeds indoors in March. Usually, by April, temperatures in southern Missouri are upper 30's low 40's. As soon as I can, I get them into a portable greenhouse with a portable heater. I don't think there is any substitute for natural sunlight. This is what I use: https://amazon.com/gp/product/B01GDV...?ie=UTF8&psc=1 You get healthy plants (though sometimes they are huge by the time I am able to transplant them.) Just my experience for what it's worth.