Backyard Aquaponics
A place to discuss aquaponics

Hi everyone:) Everything was growing just fine then all the sudden everything slowed down and my cilantro plant turned purple. It had some purpling around the edges but now it is a deep purple and no it is not cold enough where I live for it to turn purple. I read somewhere that plants can turn purple if it's too cold;)

Someone told me but I may need to add fish for more nutrients so I did just that and it seem to have gotten worse. Any ideas what this could be?

Most of my new seedlings are doing the same thing. Purpling around the edges and growth slowed.

Are these purple on the underside of the leaves as well?

It's probably a phosphate deficiency and it can be brought on by cold temps. If this is the case it should go away as the temperature warms and the plant is then able to take up phosphate because this is a mobile nutrient. FYI - I think there is a chance that parts of the leaf tissue will die and nothing will bring these back but I'd probably take a wait and see attitude on this, provided you are having cooler temps.

Phosphates are used in energy transfer within the plant as ATP so without enough everything slows down. There is probably enough in the environment but the plant can't use it as well with the cold temps so your stuck in a holding pattern until things warm up.

Forgot to mention one other thing - if this goes on too long plants can become stunted and may not snap out of it. I've seen this with corn.

I was running under the assumption that the purpling in the leaves could also be caused by nitrogen deficiency. I live in Southern California and I do not think it is ever cold enough here to turn the cilantro purple the way it is. I will take more pictures right when I can but it has gone to a very deep purple.

Thank you so much for the feedback in if you have any other ideas let me know:)

I'm not certain with cilantro but for most plants nitrogen deficiency shows up as yellowing leaves on the lower part of the plant so it's unlikely this is a nitrogen deficiency.

Assuming any phosphate problem should take care of itself because you should have plenty of this, I'm going to go with Potassium instead because of the area on the leaves that's turning purple, because cilantro contains fairly high levels of potassium and because it's a very common deficiency in AP (especially early in running a system).

Post some pics of your other plants, maybe we can get an idea from how the others look .

Look closely at the plant and see if you can figure out whether this is on old growth first or new growth.

Here is some more photos.

It's very difficult to post images on here... I guess I'll figure it out another time.

The first one I posted I guess with someone of a fluke because I've tried three different ways to post the images here and no luck. Maybe some sort of auto resizing image thing needed?

It gets easier after you've done it a few times. This is a tutorial one of the other members made - http://www.backyardaquaponics.com/forum/viewtopic.php?f=4&t=21754