Tomatoville® Gardening Forums - View Single Post - Purple underneath seedling leaves, then they curl up and die

z_willus_d · March 11, 2012

DarJones-

I found your write-up very helpful, particularly the paragraph with tips on how to detect under vs. over "Nitrogenization." Based on your descriptions, I would conclude that I have not added too much "N" into the equation, as I do not show signs of rapid growth nor the yellowing of leaves that you've described.

Rather, the seedlings continue to exhibit "purpling" of their leaves, and the stems to some extent. Usually, as I did this morning, I walk in to find a set of dead, soggy curled up leaves on a branch that falls off to the touch. Sometimes, the branch will contain one leaf that's clearly affected (purple curled up and necrotic) with a second leaf that doesn't appear so affected (regular green with less purple). It's as if the plant is tossing out the good with the bad.

My soil temps gets down to around 66F at night (room temp never below 67F). The temps rise up to between 78F and 85F (max) during the day. These have been the conditions from day1. Humidity is fairly stable at 40-43% during the day and up to 50% at night when the lights are off. I don't believe it's possible my P uptake issue, if indeed that's what's resulting in the purple, could be caused by cold soil/environmental conditions.

You mentioned a balance between P and K where too much of one can block the availability of the other. Perhaps I've somehow overloaded the plants with K (maybe with the one-time application of molasses (1TBS to 2 gal with the watering that included Mycos and Actinovate). If that were true, than I would need to either somehow sap-out the overwhelming K or add more P, though adding more of anything at this point is off the table unless I know for a certain what I'm dealing with.

To the folks using FoxFarm's Light Warrior. I spent some time measuring the pH of the Ocean Forest and Light Warrior potting mixes. I used my Hanna Instruments glass-tip pH meter after calibrating it in 7.01 buffer solution. I was surprised to find the pH was in the mid to high 5's rather than the low to mid 6's as expected. It might be worth checking your grow medium's pH if you're using these products. Sadly, I have the opposite problem in my outdoor beds where the pH is reading high 7's / low 8's (added too much lime). I've been trying to correct down with sulfur pellets and cottonseed meal, but it takes time to know to where the pH will equalize because it the sulfur, lime and cottonseed all take effect slowly as they break-down.

I'm going to try a deep watering today. Ray was right, many of my pots are dry down 1" and only slightly moist below. I remain in the dark as to what's causing the purple and more importantly branch/leaf aborts. Until I know, I'm not adding anything but water and light, and on that latter ingredient less of it based on Dice's link that suggests too much light can cause leaves to purple. I've cut the ON/OFF ratio down to 14-16H ON / 8-10H OFF.

Thanks,
Naysen

March 11, 2012	#43
z_willus_d Tomatovillian™ Join Date: Jun 2011 Location: Eastern Suburb of Sacramento, CA Posts: 1,313	DarJones- I found your write-up very helpful, particularly the paragraph with tips on how to detect under vs. over "Nitrogenization." Based on your descriptions, I would conclude that I have not added too much "N" into the equation, as I do not show signs of rapid growth nor the yellowing of leaves that you've described. Rather, the seedlings continue to exhibit "purpling" of their leaves, and the stems to some extent. Usually, as I did this morning, I walk in to find a set of dead, soggy curled up leaves on a branch that falls off to the touch. Sometimes, the branch will contain one leaf that's clearly affected (purple curled up and necrotic) with a second leaf that doesn't appear so affected (regular green with less purple). It's as if the plant is tossing out the good with the bad. My soil temps gets down to around 66F at night (room temp never below 67F). The temps rise up to between 78F and 85F (max) during the day. These have been the conditions from day1. Humidity is fairly stable at 40-43% during the day and up to 50% at night when the lights are off. I don't believe it's possible my P uptake issue, if indeed that's what's resulting in the purple, could be caused by cold soil/environmental conditions. You mentioned a balance between P and K where too much of one can block the availability of the other. Perhaps I've somehow overloaded the plants with K (maybe with the one-time application of molasses (1TBS to 2 gal with the watering that included Mycos and Actinovate). If that were true, than I would need to either somehow sap-out the overwhelming K or add more P, though adding more of anything at this point is off the table unless I know for a certain what I'm dealing with. To the folks using FoxFarm's Light Warrior. I spent some time measuring the pH of the Ocean Forest and Light Warrior potting mixes. I used my Hanna Instruments glass-tip pH meter after calibrating it in 7.01 buffer solution. I was surprised to find the pH was in the mid to high 5's rather than the low to mid 6's as expected. It might be worth checking your grow medium's pH if you're using these products. Sadly, I have the opposite problem in my outdoor beds where the pH is reading high 7's / low 8's (added too much lime). I've been trying to correct down with sulfur pellets and cottonseed meal, but it takes time to know to where the pH will equalize because it the sulfur, lime and cottonseed all take effect slowly as they break-down. I'm going to try a deep watering today. Ray was right, many of my pots are dry down 1" and only slightly moist below. I remain in the dark as to what's causing the purple and more importantly branch/leaf aborts. Until I know, I'm not adding anything but water and light, and on that latter ingredient less of it based on Dice's link that suggests too much light can cause leaves to purple. I've cut the ON/OFF ratio down to 14-16H ON / 8-10H OFF. Thanks, Naysen