Very dark seedling leaves

My tomato seedlings are looking pretty decent, most are getting their first true leaves. But I noticed that some of the first ones that sprouted are now very dark green, almost black. They are darker to me than what shows up in the image. Notice the lighter green one, that one looks normal color to me. They have been living in my basement under grow lights. Since I have them a little farther away than the 2-3 inches recommended, I've been leaving my lights on almost 24-7. Could I have burnt them? They are still growing, should I just leave them be or are they a lost cause?

They don't look burnt to me. In fact they look pretty darned good. It could be the variety or it could be something in the soil. Did you start them in packaged seed starting mix or something else?

What variety of tomatoes are they ?

For one thing, your seedlings need a rest from the light. They won't be able to take it for 24/7 and do well. Either move them closer to the light and only give them 16 hrs of it, or at least cut off the light a few hours during the night.

It may just be the variety that makes the leaves darker..... or too much light. Just wait and see what happens in another week or so. At this point they don't look like tomato leaves. Look for serrated leaves in a week or so or those shaped like a potato-leaf, more rounded.



Several tomatoes on the left last year with some peppers and eggplants, too.

quiltbea wrote:For one thing, your seedlings need a rest from the light. They won't be able to take it for 24/7 and do well. Either move them closer to the light and only give them 16 hrs of it, or at least cut off the light a few hours during the night.

It may just be the variety that makes the leaves darker..... or too much light. Just wait and see what happens in another week or so. At this point they don't look like tomato leaves. Look for serrated leaves in a week or so or those shaped like a potato-leaf, more rounded.

+1, I leave my lights on only 14 hours. The plants need a period of darkness to do what they need to do.

could it be too much nitrogen, I gave guano to my tomatoes and strawberries once and got the deepest green leaves, and LARGE and no fruits

GWN wrote:could it be too much nitrogen, I gave guano to my tomatoes and strawberries once and got the deepest green leaves, and LARGE and no fruits

if a higher level of nitrogen is the case it is not a problem at the stage of their development.

im going to look back on last years pic's of our tomato plants....if i remember right...some of mine had a purple color to them as well.....it turned out they were a bit cold.....once the weather warmed up a bit the color got better....i had my out side next to the house harding off on a table.....i dont remember if the leaves were dark or not.....i just remember a bit purple color....

is it a bit cool where your seedlings are?

hugs

rose

Sometimes a purplish tint early in the season when its still cool, means a phosphorus deficiency. Some bonemeal, rock phosphate or limestone is needed in the mix when that happens.

I see purple only on the outer fringe of the leaf. The rest of the leaves are dark green (I don't see a problem with that).

Too many hours of lighting is an issue (though I don't think that's causing the purple color in the leaves). There are ways to "trick" plants to allow for more hours, but that's a complicated subject. 14 hours is good, no more than 16 hours. They need their sleep time just like we do!!

I think the problem is a combination of the exposure to cold temps and the phosphorous deficiency. Though that does not necessarily mean the soil mix is deficient in phosphorous. So I'd hold off amending the soil; better to have it tested first.

Phosphorous deficiency can show up because of "cold root zone temperatures". Cold root zone temps have probably stopped or slowed down the uptake of the available phosphorous for the plant. Thus, the discoloration of the leaves.

Give the plants some bottom heat and see if the coloration improves. Have your Mel's Mix tested.

Here's an article from Aggie Horticulture (Texas A&M)
http://aggie-horticulture.tamu.edu/publications/tomatoproblemsolver/leaf/phos.html

---Dave

Sorry, I haven't had a chance to be online much lately. The tomatoes are heirlooms, a mix of varieties. I am using Jiffy seed starting mix. They are housed in my basement, but it is a finished basement and is always between 65 and 75 degrees. Is that too cool for tomatoes? I don't have the money right now for a heating mat, so I guess they will have to stay a little chilly. Do you all think this is something that will kill/severely stunt them?

Lisaphoto,

Your basement temps are just fine for the Tomatoes. In my last post I suggested any phosphorous deficiency was due to a cold root zone. I don't think that's the case now provided you haven't had them outside to try to harden them off (like HappyGardening said she did last year).

I think they'll be fine and grow out of it.

When you transplant out into your bed with Mel's mix that will probably fix any nutritional problem long term. If you think you need to try a correction before then, try giving them some all purpose liquid feed with your next watering. Use HALF strength with the liquid feed. See if they show any improvement a week from now.

---Dave

You all were right. I've been putting them out in the warm sun most days, and moved them from the basement to the kitchen. They have definitely gotten greener, instead of the purple and dark dark leaves. The only thing that concerns me now is they don't seem to be getting taller at the rate I would expect them to. Maybe just b/c I look at them every day. Kinda like how you don't realize how much bigger your kids are until you see a picture of them from a while back.

I found that my tomatoes and other seedlings were growing (what I considered) too slowly, even with using a fish fertilizer in the water. I decided to "up-pot" them into 4" containers with Mel's Mix. Within a week, the tomatoes had more than doubled in size.... except for the two that I did NOT transplant. After 3 weeks in the MM, the transplants are 10-12" tall and very lush, while a week ago, the two that remained in the starter mix were roughly 2-3" tall. Last week, I transplanted those last two, and today they are about 5" tall.
My guess is that your little plants may have used up all the nutrients (which aren't abundant) in the starting mix or plugs.