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Purple underside leaves and stem on tomato seedling

Posted by alendalon (My Page) on
Fri, Dec 5, 08 at 1:52

I am almost 2 weeks into growing my cherry tomato seedlings in hydro. In the pictures they're different sizes because some of them were planted between 5-10 days apart from one another. However, the oldest one which has the most leaves, seems to have its leaf tips curled upwards and the underside now is completely purple! I have been giving them seedling/cutting part A+B nutrients by DNF. Ive been given them only 1/4 strength, and the NPK on the bottle shows 2-0-2 on A and 0-1-3 on B. I also adjust the pH downwards everyday using apple cidar vinegar.

I did some research and the only problem i found associated to this was a phosphorus deficiency. I've posted some pics, i hope someone can give me an answer or solution. I was thinking just add a little bit more of solution B to increase phosphorus, but that will also increase potassium as well, so before i start playing with nutes I thought id get some advice from you guys first on what to do. and yes this is my first grow in hydro lol a little more about the setup...

5 - 16watt daylight CFL's (will be adding alot more and higher wattage when these guys get a bit bigger, have y apapters coming in atm)

ebb&flow system, 2.5 gallon reservoir.

if you need more info, let me know.

Follow-Up Postings:

RE: Purple underside leaves and stem on tomato seedling

and another picture... you can see the leaves curling up and looking very purple underneath

RE: Purple underside leaves and stem on tomato seedling

well firstly, your images aren't showing up and the broken image links to a pot site.

But ASSUMING you really are growing tomatoes, what is the pH range you're maintaining? have you considered a commercial pH adjustment. I believe they typically use phosphoric acid and from the name you can guess what a byproduct of that is.
If your plants have roots coming into contact with the nutrient or coming out of your medium, you're using too weak of a solution. a full strength veg solution is what you should be using.
The only other thing I can think of is you've somehow locked up the phosphorus when you mixed up the nutrient batch. is there a precipitation in the bottom of your reservoir?

Here's a chart that shows nutrient availability versus pH. Print it out. its a very valuable to to have.
Link in case the image disappears.

RE: Purple underside leaves and stem on tomato seedling

yes, on that website i figured i'd get more responses but I guess no one really reads the gardening section there, did not get any advice from them. What do you mean exactly by precipitation at the bottom of the res? but I will add a full strength seedling nute solution, and let you know how that helps things.

RE: Purple underside leaves and stem on tomato seedling

Up your phosphorus and magnesium and the purple color will go away.

Many times, there is enough magnesium in tap water to do the trick. The phosphorus usually comes from the nutrient solution.

I use home-made organic nutrients and am not familiar with the two-part stuff, so before you go adding chemicals, better wait for some more responses from the rest of the crew here on the forum.

RE: Purple underside leaves and stem on tomato seedling

I flushed out my reservoir, ran pH adjusted water through the system for an hour, and added 3/4 strength seedling nutes that I had by DNF, and it looks like the toms bounced back strong and are looking great.

also, If someone could tell me how to attach a pic it would be great.

RE: Purple underside leaves and stem on tomato seedling

<img src="[web address]">

remember to include the whole web address (including http://) or it won't work.

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