Seedlings keep mysteriously dying off.

[JimmyNardello]

I'm in Zone 6a. Last year, I successfully grew tomatoes for the first time. A lot of them. Paul Robeson, Super Sweet 100, some beefstake varieties, to name a few. Some were in containers, and others were in the ground. To my surprise and joy, and through a drought, a heatwave, a derecho, and several strong storms, I was left with more tomatoes than I knew what to do with at the end of the growing season.

And this success was despite early neglect and less than favorable conditions. My starts were grown in a foggy window, and I had several trays that were left sitting in small pots much longer than my container tomatoes. They weren't put in the ground until early June. Somehow, they managed to produce, too.

This year, I decided I wanted to try something different, and hopefully better, than what I'd done before. I set up a shelf with BoostGro LEDs, germinated the tomatoes, and put them about 8 inches under the lights. Initially, they did well, but problems quickly came up. Some barely made it up without flopping over. Others grew well, then suddenly yellowed, browned, curled up and eventually died. Some persevered, but were left severely stunted. Some of the same issues were occurring in other seedlings, too. Yellowing, browning, and the like.

I was dumbfounded. There were several things, I thought, that could've led to this.

1. Fungal problems. The medium I used was an organic potting mix, full of wood debris. I had sifted most of it out and put the finer mix into the seedling trays. After a while, I noticed that random mushrooms started coming up in different cells. I'd pluck them every morning, and every other morning, they'd show up again.

2. Over-watering/under-watering. I may have over-watered or under-watered the cells once or twice, because I water from the top and don't have a tray system at the moment. I'm not sure if this is it, either.

3. Something to do with the LEDs. Maybe they were too close, not powerful enough, or too powerful. I'm not sure.

After almost an entire batch was dead, I tried again. I sterilized the cells with hydrogen peroxide, rinsed them thoroughly, and tried again with some leftover Black Gold seedling starting mix from last year. The same issues occurred. Some wilted, some browned, and others just simply fell over. It was getting frustrating. So I started again. Sterilized some new cells, bought some Jiffy seedling mix, and started more tomatoes. They sprouted and started to look happy, and then started flopping over.

OK. Let's do what I did last year, then, I thought. I recently started new tomatoes and put them in the window, while watching them carefully. For the first time, they were a deep, happy green. Then some of them started getting floppy again. I decided to bottom water the cells in a small bin, but it doesn't seem to have changed anything.

What's going on?

Some pictures.





Other seedlings.

[Cole_Robbie]

LED lights can be too strong if too close to the plants. Also, your media mix might need some perlite to lighten it up. Seedling also don't need nutrients until the second set of leaves, idk if the fertilizer in the mix might be too much for them. Some bagged mixes can also be contaminated with herbicides. Trying a new mix would be the first variable to change.

[Wildcat82]

Agree the grow light might too strong. The same thing happened to me when I left my grow lights on nonstop for 4-5 days when I was out of town. Normally I try to give the seedling at least 8 hours of darkness. You might want to back off watering as well.

[MissS]

I also agree with the LED's being too close to your plants. LED's need to be further away from your plants than the florescent tubes.

I am creating a mirror of this thread in the Disease forum so that any newbies or lurkers having the same problem can find the answer there.

[Seven Bends]

There may be an issue with your lights, as others have said, but that wouldn't explain why you're now having the same problem with seedlings in a window which aren't under the lights. Maybe you have two problems, the lights and something else.

The symptoms you've described and the pictures are consistent with over-watering. Little seedlings don't need much water at all, and if you over-water them, the roots will die, so the seedlings can't take up water, and it may end up looking like they're thirsty so you water more, and that just makes it worse. Are the cellpacks sitting in something that holds water (a tray, etc.), so the soil might be really saturated? Are the drainage holes clear? How much water are you putting on the plants, and how often? Are you waiting until the cellpacks get somewhat light (weight) and look a little dry on top before watering?

When your previous seedlings died, did you pull any of them out and look at the roots? That will help you diagnose the problem. If the roots are white and vigorous, over-watering isn't your problem. If there are very few roots, or they're very small, or they're brownish or yellowish at all, it's probably over-watering.

Based on your pictures and description, I doubt under-watering is your issue. That tends to be a pretty obvious cause-and-effect.

Are you watering with regular tap water? Are you adding anything to the water? Do you have a water softening system in your house?

Did you add anything to the growing medium, like fertilizer, or something to alter the pH, or anything at all other than water? The tip burn in your last picture is consistent with fertilizer burn, but that symptom can result from other things also (including over-watering). I grow my seedlings in various potting mixes that have fertilizer already in them and haven't had a problem, but fertilizer included in the potting mix could be an issue if you're also watering with a liquid fertilizer or added any other nutrients to the mix. Seedlings don't need fertilizer right away, and too much is harmful.

Did you scrub out the cell packs with soap and hot water, getting them thoroughly clean before disinfecting them with hydrogen peroxide? The scrubbing step is important. I usually just wash with soap and hot water and skip the disinfecting, but I would use a bleach solution if I had a possible disease problem.

How warm is your growing area?

What are the sticks that are visible in the pictures? Is it possible they are toxic somehow? Kind of far-fetched, but I'm trying to think of all possible reasons for your problem.

My guess is over-watering, as the simplest explanation that fits the symptoms and pictures. Good luck, and don't give up!

[Labradors]

I would blame the potting mix. Did it have manure in it? I bought some fancy potting mix last year which contained manure and bark chips. The man at the nursery who sold it to me was very enthusiastic about it. First, I grew an Amaryllis bulb, then some Maglia Rosa tomatoes. The problem was that I couldn't tell if it was too wet or too dry! It would look wet on top, but the pota would feel light, and the plants would complain so I watered, then I felt that they were too wet. I couldn't grow anything in that mix and I've been gardening for years and never had problems growing anything before!

BTW mushrooms are actually a good thing .

Linda

[Mark_Thompson]

I would blame the potting mix.

Linda

Which one? OP tried three different potting mixes and had same problem.

[bower]

Mushrooms in the seedling area/potting mix means overwatering, for sure.
Assuming that the leaf rot is also a fungus of some kind, there are likely spores all over the place. That would explain the repeat performance in different circumstances, and means you need a general purge of the whole area and an air change before it will be seedling safe again. Get a fresh unopened bag of potting mix, plan to water less, and you should be fine as the first.
I had some funk on my tomato leaves this year because I didn't do the thorough cleanup between all the winter greens and then the tomato starts. Okay, in fact it was even longer than that. And actually, the whole room could use plaster and paint.
Anyway, I use hot water Dawn and vinegar to clean everything non metal for antifungal purposes, including window. May need to go with chlorox for the light fixture which is metal; I just wiped it down with soap and water this time.
Small changes in temperature and relative humidity from season to season can have disproportionate effects on seedling starts and the amount of water they use. Less sun, less growth, less water consumed. Higher relative humidity, slightly lower temperature, overwatering suddenly favors every spore that was lurking around. Your foggy window probably didn't have any spores the first year. But that has changed.
The other thing to do in a funky season is to religiously pick off every bit of funky plant or leaf and carefully dispose. Never leave a moldy leaf sitting amongst healthy seedlings for a whole day.

[Kurt]

Too wet.Here in 10B we use the 6 inch deep conical trays,mixed with course vermiculite,rice hulls,coco coir.The squares make a root system for other plants it seems.Looks like overcompensating watering as we all have done in the past.Let them dry out before watering,if they reach for the sun they should make it

[JimmyNardello]

Maybe you have two problems, the lights and something else.

Are the cellpacks sitting in something that holds water (a tray, etc.), so the soil might be really saturated? Are the drainage holes clear? How much water are you putting on the plants, and how often? Are you waiting until the cellpacks get somewhat light (weight) and look a little dry on top before watering?

When your previous seedlings died, did you pull any of them out and look at the roots?

Are you watering with regular tap water? Are you adding anything to the water? Do you have a water softening system in your house?

Did you add anything to the growing medium, like fertilizer, or something to alter the pH, or anything at all other than water? The tip burn in your last picture is consistent with fertilizer burn, but that symptom can result from other things also (including over-watering). I grow my seedlings in various potting mixes that have fertilizer already in them and haven't had a problem, but fertilizer included in the potting mix could be an issue if you're also watering with a liquid fertilizer or added any other nutrients to the mix. Seedlings don't need fertilizer right away, and too much is harmful.

Did you scrub out the cell packs with soap and hot water, getting them thoroughly clean before disinfecting them with hydrogen peroxide? The scrubbing step is important. I usually just wash with soap and hot water and skip the disinfecting, but I would use a bleach solution if I had a possible disease problem.

How warm is your growing area?

What are the sticks that are visible in the pictures? Is it possible they are toxic somehow? Kind of far-fetched, but I'm trying to think of all possible reasons for your problem.

The lights were definitely one of the first things I considered when problems started coming up, but the fact that I started new seedlings in a different location and am still experiencing problems is puzzling.

No, the cells aren't sitting in anything, and the drainage holes are quite big. I usually water a little when the top of the soil is looking dry, but not much. Maybe about a small shot glass or two. I've been getting into the habit of feeling the weight of the cells with this new batch.

I did look at the roots of the dead seedlings when I pulled them out, and I can find the pictures later, but I can tell you that they all seemed healthy. They were all white and vigorous. No browning or any strange discolorations that would indicate any kind of rotting or other issues, from what I could tell.

I water with tap water, and no, I don't add anything to the water. I also don't have a softening system, but I know for a fact that the area I'm in has terribly hard water. This wasn't something that caused problems last year.

Nothing was added to the medium other than what it came with. It was Back To The Roots potting mix, which, in retrospect, has terrible reviews and I see lots of people complaining of mold and other issues. But again, I started again in two different mixes. Jiffy, and Black Gold. Is it possible that fungal issues killed my seedlings and has spread to the new batch? No idea. I think this is something that would've shown in the roots, though.

I did not use soap or scrub the cells, but I did wipe them down thoroughly before and after soaking them in hydrogen peroxide.

My house is older and doesn't have central heating, so it was quite cold in the beginning of the year. Maybe between 50-60F when I first started. Still, the seedlings did relatively well until these issues came on.

The sticks are just bamboo skewers with labels attached to them.

[JimmyNardello]

Mushrooms in the seedling area/potting mix means overwatering, for sure.
Assuming that the leaf rot is also a fungus of some kind, there are likely spores all over the place. That would explain the repeat performance in different circumstances, and means you need a general purge of the whole area and an air change before it will be seedling safe again. Get a fresh unopened bag of potting mix, plan to water less, and you should be fine as the first.
I had some funk on my tomato leaves this year because I didn't do the thorough cleanup between all the winter greens and then the tomato starts. Okay, in fact it was even longer than that. And actually, the whole room could use plaster and paint.
Anyway, I use hot water Dawn and vinegar to clean everything non metal for antifungal purposes, including window. May need to go with chlorox for the light fixture which is metal; I just wiped it down with soap and water this time.
Small changes in temperature and relative humidity from season to season can have disproportionate effects on seedling starts and the amount of water they use. Less sun, less growth, less water consumed. Higher relative humidity, slightly lower temperature, overwatering suddenly favors every spore that was lurking around. Your foggy window probably didn't have any spores the first year. But that has changed.
The other thing to do in a funky season is to religiously pick off every bit of funky plant or leaf and carefully dispose. Never leave a moldy leaf sitting amongst healthy seedlings for a whole day.

Adding to this, I should mention that my house has terrible air circulation. My central air hasn't worked in a while, and I usually don't run fans or an air conditioner until I have to. I assume this stagnant air makes a perfect environment for spores, and maybe that's why the problem has persisted with the seedlings that are now in the window. I wanted to get a dedicated clip-on fan for the seedlings to encourage better airflow, but I haven't gotten around to it. An air filter does run in the room they're now in, but that's about it. Not sure what else to do, other than try and start seedlings outside and hope for a better outcome.

[pepperhead212]

Sorry to hear about your ordeals with the tomatoes! I can't tell you anything about that particular LED, and 3 different seed mixes make it sound like it's something else added, but maybe every time. Being a cheapskate, I haven't bought seed mixes for years, as expensive as they've gotten! But even when mixing the peat and coir (no exact ratio - whatever is on hand), perlite (around 20%), just a little vermiculite, and some worm castings (about 10%), I mix it up thoroughly, then fill a deep, foil pan or two, then sterilize in a 200° oven, or on my gas grill (depending on how warm it is outside, though it is usually cold). Then, when cool, it goes into a clean bucket, and I wet it, with some water with some Bt israelensis in it (won't help with your problems, but I do this to prevent the inevitable fungus gnats), and mix a little micorrhyzae into it - this is something that I think helps these things a lot. The damp mix sits until planting time, and it doesn't take long before the micorrhyzae becomes visible, and only takes a tsp or so of granules/gal of mix. I use this also in the mix I make up for my SIPs, and other outside containers, without sterilizing it, like I do for seed starting, and it works well there, too, and I only use about a tb in about 13-15 gal of mix.

[Seven Bends]

No, the cells aren't sitting in anything, and the drainage holes are quite big. I usually water a little when the top of the soil is looking dry, but not much. Maybe about a small shot glass or two. I've been getting into the habit of feeling the weight of the cells with this new batch.

I did look at the roots of the dead seedlings when I pulled them out, and I can find the pictures later, but I can tell you that they all seemed healthy. They were all white and vigorous. No browning or any strange discolorations that would indicate any kind of rotting or other issues, from what I could tell.

I water with tap water, and no, I don't add anything to the water. I also don't have a softening system, but I know for a fact that the area I'm in has terribly hard water. This wasn't something that caused problems last year.

Nothing was added to the medium other than what it came with. It was Back To The Roots potting mix, which, in retrospect, has terrible reviews and I see lots of people complaining of mold and other issues. But again, I started again in two different mixes. Jiffy, and Black Gold. Is it possible that fungal issues killed my seedlings and has spread to the new batch? No idea. I think this is something that would've shown in the roots, though.

I did not use soap or scrub the cells, but I did wipe them down thoroughly before and after soaking them in hydrogen peroxide.

My house is older and doesn't have central heating, so it was quite cold in the beginning of the year. Maybe between 50-60F when I first started. Still, the seedlings did relatively well until these issues came on.

The sticks are just bamboo skewers with labels attached to them.

A room temperature of 50 degrees is pretty cold for tomato seedlings, and cool temperature combined with fungal spores in the air is a ticket to problems. A temperature of 60 degrees is probably okay, but 65 degrees (daytime) would be better.

If you're going to start over, maybe buy a package of 3-oz Dixie cups or Solo cups so you're sure you have something uncontaminated to plant in. The small size and individual nature of the cups (as opposed to cellpacks) also makes it easy to be sure you're watering correctly. Drill or poke drainage holes in the bottom, of course. Unfortunately, you're probably going to need to buy a new bag of seed starting mix so you're sure that's uncontaminated also. Or you can sterilize any remaining mix by cooking it in your oven.

If you're going to reuse your cellpacks or pots, thoroughly scrub them with dish detergent and hot water before disinfecting them. Get all the soil bits and gunk out of them. The effectiveness of some disinfectants can be reduced by the presence of organic matter.

As I mentioned, I would use bleach solution. Hydrogen peroxide is an effective disinfectant, but it takes longer to work - you'd need to soak things longer. Also, hydrogen peroxide loses effectiveness pretty quickly after you open the container (a few months), so you need to be sure what you're using is fresh. See this study of various disinfectants: https://www.cdc.gov/infectioncontrol/gu ... mical.html.

I believe @Bower gave you good advice about cleaning and disinfecting the room you're growing in.

Sunlight and warmth solve lots of problems, so you'll probably have better luck if you get the seedlings outside. If it's still chilly where you are, you can make a mini greenhouse with a clear plastic file box or storage tote. Just be careful not to cook the plants in bright sun/warm days.

[JimmyNardello]

Sunlight and warmth solve lots of problems, so you'll probably have better luck if you get the seedlings outside. If it's still chilly where you are, you can make a mini greenhouse with a clear plastic file box or storage tote. Just be careful not to cook the plants in bright sun/warm days.

This was pretty much the conclusion I've come to. I plan on just starting them outside this time, considering that last year, I planted stunted and rootbound tomatoes in June that ended up outcompeting the larger ones I put in containers early on. They produced a good amount of fruit in August and September and were some of the tallest tomatoes I've ever seen. I think I still have plenty of time to start over.

Just sad about all the potential that was lost to whatever this is.

[bower]

I missed your comment about the temperature, but Seven Bends is exactly right, 50F is too cold. The tomatoes won't be doing anything at that temperature. I have an unheated seed starting area too, but mine is usually around 60 F, maybe a bit cooler at night when lights are off and next to the window. This is where seasonal variation can make a bigger difference than you expect, because the base temperature is already marginal.

So starting later might actually be just the ticket, as long as your weather has warmed up.

[slugworth]

too wet
Your seed starting mix looks questionable,possible wrong PH

[JimmyNardello]

Little update. I put a batch I started inside that was having these problems outside, without hardening them off first. I figured they were going to die, regardless, and planned on starting more exclusively outside.

The next day, I come out to check on them, and they've somehow gone from spindly, floppy little seedlings to strong, healthy ones with a deep green tinge. In a day. There was even one that survived the initial onslaught, a Tula, that's now putting on rapid growth after a month of stunted growth.

I honestly wonder how much the initial problems had to do with airflow and light, because that's all that I've changed, aside from switching to bottom watering. Pretty amazing turnaround.

[ddsack]

There is nothing better than real sunlight and open air. I think people baby their seedlings in the house too long. If the outside temperature allows, they are way better outside in 55+ F as long as it is sunny outside, even when very small. I know the problem for working folks is it's too cold to set them out early before leaving for work for the day, and you have to watch the weather forecast for thunderstorms while at work if no one is home to rescue them. So outside is not practical for many. Before I had a greenhouse, I built a simple 4'x4' coldframe type box from a cheap 4 ft wood lathe bundle and clear plastic. I made squarish panels that were wired together with eye screws in the corners, and could be wired or tied to a fence for stability. Although I made a top panel I could later use at night, I left it off during the day because the heat would be too hard to regulate in full sun, plus good ventilation. The seedlings were mainly protected from direct winds, the sides were probably around 30" high, I don't remember exactly. Had to bend at the waist to put seedling trays inside. But one front side had clips that could be opened so as to swing open for access also. The high sides provided a nice heat sink because the wind was mostly kept out.

[Seven Bends]

Getting seedlings outside is the best way to heal them from over-watering. Sunlight, wind, warmer temperatures and lower humidity all increase transpiration rates. The increased transpiration helps the plant get rid of its excess water and helps dry out the water-logged soil.

[pepperhead212]

Little update. I put a batch I started inside that was having these problems outside, without hardening them off first. I figured they were going to die, regardless, and planned on starting more exclusively outside.

The next day, I come out to check on them, and they've somehow gone from spindly, floppy little seedlings to strong, healthy ones with a deep green tinge. In a day. There was even one that survived the initial onslaught, a Tula, that's now putting on rapid growth after a month of stunted growth.

I honestly wonder how much the initial problems had to do with airflow and light, because that's all that I've changed, aside from switching to bottom watering. Pretty amazing turnaround.

Glad to hear the plants are getting better! Hope they keep getting better, as well as any future plants.

You're mention of "airflow" reminded me of something I do every year, that I didn't even mention - about a week before putting them out for the first time, I set an oscillating fan on a timer, first just a couple hours a day, several times, then increased to 4 or 5 hrs, and off a couple, then back on. This helps them get ready for that wind outside, plus dries them out a little faster, and gets them ready for that.