I have had some tomato seedlings growing in my little green house (or grow room) for about a week now. This morning I went down to check on everything (I check morning and night) and tonight I noticed a issue. Some of my tomatoes have died. I took one out and took a closer look and noticed that the top (leaves) was fine, the root was fine, but the middle wasn't. It was all dried up. I don't understand what is going wrong. This happened to 5. The rest are healthy, but this is a threat to me. A threat because this is the first year I have every started my own seeds and I don't know if I am doing something wrong or if this is common. Any help would be greatly appreciated(SP?).

Update: I have now got a picture of the tomato. Amazingly it still has a healthy looking top, even though I found it like this last night, I thought it would be dried up by now.

Also I figured to mention my soil mixture and water habit. The soil is Miracle grow potting mix (50%) and then coco coir (50%). When it comes to watering I wait till the soil is nearly dry and add some into the tray underneath the cell tray, so the water soaks in from the bottom.

Tomato seedling

So there it is in the center, if the grow light messes with your eyes and prefer normal light I could get my portable flood light and get another picture, just let me know.

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    Hi! It sounds like something sad is happening to your tomatoes, but I don't need to tell you that if anyone can help you, we can! (It can't be me, though, I don't grow vegetables!) When you come back and post your pictures, would you mind re-wording your title as a question asking something related to what the problem is? That way, people will know at a glance what the question's about. Also, we don't use emojis, so that would have to be deleted, please. I look forward to seeing you get some help. By the way, I love your bunny avatar! Apr 12, 2018 at 3:40
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    Can you cut through the dried up stem region to see if it's black? Apr 12, 2018 at 5:53
  • @GrahamChiu I took one towards that back that was dead and gone and cut the area that is dried in half like you asked. Taking a close look it was still green, a dark green but green.
    – Ljk2000
    Apr 12, 2018 at 12:11
  • Thanks for understanding, and for the edit. It looks great. We might as well delete these comments since we don't need them anymore. Thanks! Apr 12, 2018 at 19:35

1 Answer 1


I don't usually like to answer my own question, but I did find what is happening so, here is the answer...

What is happening to my seedlings is something called "Damping off". This is a fungus that grows on top the soil in the right conditions. There are few different ways to get this fungus growing.

  • Over watering (wet soil all the time)
  • Planting media infected with spores
  • Trays not disinfected (which can be done with 10% bleach water, let pot sit for 30min)
  • No air circulation
  • Watering with cold water (shocks the plant, weakening it for a while)
  • reusing potting mix

In my case I think it was my watering. I have a tray beneath the cell tray that holds the water. I put water in that tray and the soil/coco coir mix soaks the water to the top, giving the plant water. I do this because the heat mat has a chance to heat the water, which actually prevents this fungus. But since the soil is always moist-wet I accidentally made a good growing condition for the fungus as well as the plant.

For me to solve this issue I have to get a fungicide to kill the fungus and save the remainder of the tomatoes. As for prevention if I want to keep my watering method I need to have some airflow over the top of the tray, to dry the very top of the soil.

Source: https://www.extension.umn.edu/garden/yard-garden/diseases/damping-off/

  • There is nothing you can do for damping off fungus...a fungicide will not control it or kill it. Fungicides are like a raincoat, protective not a cure. Do not do the watering from the bottom. This fungus is everywhere, if you've got the right conditions you will start to see problems. No fungicide should be used. Dump out old soil and plants, clean with bleach, use fresh potting soil (germinating soil), no fertilizer and start again. Don't soak the soil when you water until that plant has roots beginning to come out of the drain hole. Moisten, do not soak.
    – stormy
    Apr 24, 2018 at 4:25

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