Purple stems on tomato seedings

First time growing tomatoes from seeds. Started them on a seed mat and then moved to a grow light after germination. However, I've noticed all of them starting to get purple stems. Is this normal? The internet seems to say many different things on the topic! Is it normal? Not enough nutrients? Too cold? I've attached a picture of one of the plant as well as my light set up.

totally normal in certain varieties, especially high-anthocyanin varieties like those with ‘black’ in their name!

Ah gotcha! It does seem to be affecting all of my tomato plants though. I'm growing:

Brandywine, Lillian's Yellow, Roma, Early girl, Sun gold and Sweet Million.

Like you, I've gotten bitten by the "plant all the tomato variety" bug. But since I have far too many plants and not enough places, choices had to be made.

I'm also growing some brandywine pink, so far none of them have a purple stem but they still have no true leaf. However, some of the Black Krim I have growing are starting to have their stem turn purple (and as their name suggest, their color range in the black, like the one in your picture.) I never grew Black Krim before and never noticed the purple stem on the brandywine pink. I honestly have never heard of plants turning to any color other than yellow, brown, white... when they had some sort of nutrient deficiency. If there is a nutrient deficiency, the first place I would look is with the leaves, or the overall growth of the plant, but I'm FAAAAR from being an expert. I'm still killing way too many plants this year.

Mike Lafay wrote:Like you, I've gotten bitten by the "plant all the tomato variety" bug. But since I have far too many plants and not enough places, choices had to be made.

Yes I've been really excited to different varieties this year. Plus I'm excited for my kids to see all the different colors/shapes/sizes of tomatoes.

The purple color has yet to reach the leaves yet (they are just getting their set of true leaves). I'm thinking I'll just keep an eye on them as they grow. I don't want to overact and try and make a correction that could damage them even more.

What kind of grow lights and bulbs are you using? I have couple of LED grow lights but the majority are florescent T8 lights, each unit having one cool light and one warm light. The florescent lights have a more full spectrum of wavelengths, especially with the cool and warm bulbs combined. LED lights are so energy efficient because they only produce wavelengths of light for whatever they are made for. If you were completely growing indoors, you would need different LED bulbs for growing leafy vegetables as opposed to fruit, like tomatoes. I've noticed plants under the LED lights have different coloring in response to that limited spectrum of light. On the plus side, as long as they are hardened off sufficiently, it doesn't seem to bother the plant in the long run.

I'm using the GE LED grow light. It's 40w and 72 PPF. It states that it's a "balanced light spectrum" specifically made for seeds and greens. This is my very first grow light. I picked up a couple at a local overstock shop for 1/3 of what they normally cost. I plan on transplanting to my garden (or my patio for my herbs) here in a month or so. As you can see, I have two set up. I have one lower to the seedlings for my peppers, cucumber and tomatoes. My second one is higher up, as I am going to be getting herbs under that one next.

Be careful if transplanting early. If I understand USDA hardiness zone correctly, you live in a colder zone than me.

Usually it's good to transplant after mid-may to avoid any late frost. However it's not an absolute rule. Last year I tried planting corn two weeks before that, ready to plant again in case of a late frost. There was no more frost this year, so my corn was able to grow earlier.

Gradually hardening the plants is a good idea, although tomatoes are very hardy (except toward cold) so it's not absolutely required..

If your plants happen to grow too much inside (I don't know the english word yet for that) and have a big stem, it's recommended to cut the first few leaves, and cover the plant stem all the way up to the first remaining leaves with soil. which may involve laying the plant down. When covered, the stem will make roots, meaning a better nutrient absorption, so it's not limited to overgrown plants. There's a lot more tomato stuff to be said, but I'll stop there unless you need more information on that subject. My plants are calling me and I have to take care of them.

Very true, some varieties have lots of purple in stems and leaves.  And lighting can have a big impact.
But, if your seedlings fail to thrive you can Google the words.....
Phosphorous/Potassium/magnesium  deficiency in tomato plants. Look at the pictures and descriptions.  or....
Go more broad spectrum. Google the words ... Mineral deficiencies in vegetable plants.
Mineral deficiencies can look very different in different plants but they are very easy to overcome!
Lots of good pictures online.
Happy gardening.