Tomato Seedling 911: Yellow & Purple is not a Fashion Statement

Tomato seedling with a phosphorus deficiencyI can remember it like it was just a few weeks ago. I was all proud of my little tomato seedlings. They were growing up so big and strong, putting out all kinds of healthy green leaves. I took them out of the nursery and that’s where the problems began.

Those little tomato seedlings decided they wanted to be different. They went and colored their leaves yellow and purple. Started looking sullen and just didn’t perk up any more when I came in the room.

At first I figured is was just a passing phase, something they would grown out of. Then one day, I came in to find two of them laying on the ground, non-responsive. I rushed to help them, but it was too late. They were gone. It was then that I made my decision. My little tomatoes needed an intervention and fast before any more of them took their own lives.

At first, I felt like I was all alone. Like somehow I had failed them. Had I not provided enough food for them? Did I not feed them right? Or perhaps I had not had them in the right light?

But then I found that other gardeners have this problem too with their tomato seedlings. Yes, I had failed them, but not in the way I thought I had. I had let them out of the nursery too soon was were I had failed.

My little tomato were suffering from a phosphorus deficiency. At first I was surprised because I had specifically added phosphorus in the form of bone meal to the soil before planting them. The issue is that, apparently, if tomato seedlings do not get enough heat, they can’t take up the phosphorus in the soil.

When I took my seedlings out of the plant trainer, I also took them away from the heating pad that I had under the plant trainer and put them in the direct path of drafts from the back door. Oops. Live and learn and kill a few seedlings along the way.

But the problem has been solved and my tomatoes are now in a tomato heating rehabilitation facility. I think that if they complete the one month program, my little tomatoes can live out the rest of their lives as the happy and healthy little plants that I know they can be.

3 thoughts on “Tomato Seedling 911: Yellow & Purple is not a Fashion Statement
  1. Christian Janke on

    I encountered the same problem a couple weeks ago with about 60 or so of my seedlings that I hadn’t yet transplanted into 4″ pots. What’s weird to me is that I’ve read in many books and tomato websites that you should keep your seedlings at 65 F degrees and it’s even ok if the temp in the room drops to 55 at night to help fool them into producing fruit earlier. My room temp has stayed at a pretty constant 65 degrees, so after discovering the cause for the purple leaves I’m fairly confused as to why my seedlings did turn purple. I transplanted my first set of 30 seedlings into 4 inch pots when they reached about 2 inches tall before they’d started growing their first set of true leaves and none of them had the “Purple Leaf/Phosphorus deficiency” problem. It happened to the other 60 that I left in the 6 pack cells that turned purple. And I noticed it after about 1 week from the seedlings growing their first set of true leaves.
    I went ahead and transplanted about 30 of the remaining 60 into 4″ pots(using warm soil and warm water) and about 1 week later they’ve started growing out of the “Purple Leaf” problem. I also put them back on the heat mats to see if that will help.
    I am wondering if by keeping the room in the house that the seedlings are in at that recommended 65 to 70 degree temperature, really doesn’t serve or penetrate the tomatoes and or soil as well as a greenhouse would at a 65 to 70 degree constant temperature or by using heatmats all the way through the 6-8 week seedling growing time period at a 65 – 70 degree temperature.
    These are my experiences, results and thoughts on the “Purple Leaf/Phosphorus Deficiency” problem.


  2. J Rogier on

    Oh, my, Tomatoes 911 is about the funniest, delightful read in about 100 years. We searched b/c our san marzano TREASURED little guys are croaking…. Thanks! Thanks! Joy.


  3. Heather on

    You guys are great! I am going to see if heat will save my purple babies as well, I’m a little confused to, as all my seedlings are in the same temperatured environment, but not all are purple, but I thouroughly enjoyed this read!


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