Purple color on my seedlings

[augiedog55]

I'm new to growing tomatoes from seeds. I grew some as an experiment this summer to practice a bit. I grew them to about 5 inches tall before i ended the experiment. they grew fine. I have two aussie seedlings i just potted up(they had their first true leaves.) Up to this point they are doing fine but today I notice the second set of leaves started to appear todayand i noticed the the first set of leaves and the origonal set of leaves were curled down a bit and the back of the leaves are purplish. Is it anything i should worry about growing seedlings? I'm still in the practice mode.
thank for any help

[FILMNET]

Thats fine sometimes the tiny stems are purple
Also the first leave will fall off dont touch them, if you look at them they all look the same tomatos of different plants with the first 2 leaves. That why sometimes if you mix up seedlings you have to wait for these next leaves

[Fred Hempel]

purple = stress and germination is stressful

Some plants exhibit more purple (anthocyanin) than others

I wouldn't worry unless the leaves are yellowish too. Then there are a checklist of stresses to start thinking about. Water stress (too much or little). Nutrient stress (too much or little). Heat. Cold. Light stress (too much or little).

[Wi-sunflower]

Around here plants will often turn purple when it gets cold. The plants can't take up the Phosphorus. Warm them up and the purple will go away.

Carol

[carolyn137]

Originally Posted by Wi-sunflower

Around here plants will often turn purple when it gets cold. The plants can't take up the Phosphorus. Warm them up and the purple will go away.

Carol

Agree with Carol. The main reason that leavesof seedlings turn purple is b'c P can't be transported when the seedlings are too cold.

Yes, you can warm them up, or you can spray them with a low NPK product like fish or algae stuff which have lots of micronutrients,and that can do the trick as well.nd that's b/c the P is directly absorbed thru the leaf surface which avoids take up of P via the roots.

Or you can do as I used to which is just to ignore it b'c it does go away.

And yes, even after transplanting out if there's a cold spell the larger plants can turn purple and sometimes even yellow, but that too is reversible and I ignore that as well.

Carolyn, whois very good at ignoring lots of issues when growing tomatoes.

[Fred Hempel]

You have to ignore lots of issues. Tomato plants have so many ways to become ugly.

[Cole_Robbie]

Originally Posted by Wi-sunflower

Around here plants will often turn purple when it gets cold. The plants can't take up the Phosphorus. l

aha! I was thinking phosphorous deficiency, but didn't understand why.

[Wi-sunflower]

Hubby used to be in the turf business for many years. First as a golf course superintendent (think Bill Murray's boss in Caddy Shack) and then in fertilizer sales.

If someone thought he had a turf disease because of "off color" grass, the first thing they would do was to take a plug from the area and take it into a warm room. More often than not, it would change colors almost in front of your eyes as it warmed up. Or at least by the next day.

Carol

[FILMNET]

But he is talking about seedlings with the 2nd leafs, if you do anything easy with them.

[augiedog55]

Thanks for your advice. I'm practicing with these two plants. The temperature where they are is 70 degrees.

[carolyn137]

Originally Posted by augiedog55

Thanks for your advice. I'm practicing with these two plants. The temperature where they are is 70 degrees.

That's warm enougth so here's the question.

Is it leaves that are turning purple on the underside or just stems and petioles and the like. B'c if the latter that's normal for many, but not all varieties.

Carolyn

[Fusion_power]

Production of anthocyanin is a normal response for most tomato varieties. Most of us see the purple leaves and stems and think the color represents something wrong. It doesn't! This is a normal chemical produced by a plant to defend itself against excess light and pests. Guess what most of us do when we are growing seedlings indoors in winter? We put them under very bright lights that don't have the right balance of ultraviolet. So what do the plants do? Well, if they have the genetics to produce anthocyanin, then the leaves and stems turn purple. So this is a stress response, but the stressor is not cold, it is bright lights that do not have the proper amount of UV. But read on, this story continues.

The actual signs of cold stress are yellowing leaves, curling leaves, slow growth, and spindly stems. There are two parts to this stress. The first is caused by reduced root efficiency for absorbing potassium and phosphorus. The second is the leaves and stems which do not have effective genetic mechanisms to deal with low temps. The leaves in particular reduce transport of photosynthate and produce less plant sugars. Guess what happens when you combine bright lights with plants that are growing at less than optimum? Well, that thing called a "stress response" happens and the plant produces anthocyanin trying to protect itself in the face of overwhelming bad growing conditions. End result, purple leaves.

Why is a tomato plant so intolerant of cold? Tomatoes originate in the tropics. They are tropical plants which we are trying to grow in a temperate (think NOT tropical) environment. There are two wild species of tomato that are able to grow at higher altitudes up to 2 miles high where temperatures routinely get down to 0°F to 15°F yet are fully hardy true perennials. So from a genetic perspective, there is a lot of room to improve cold tolerance of our tomatoes.

DarJones

[ddsack]

Nicely explained, Dar! I kinda sorta knew this from experience, but you made it much clearer and understandable. Thanks for posting!