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Purple Cotyledon Drop, Tryin to Fix the Issue...

What's up everyone? If you haven't been following my Glog, I have been fighting a loosing battle with getting my seedlings past the cotyledons (seed leaves [I had to Google it the first time I saw it]). Basically, they have purpled and dropped. Since the cotys drop, they are unable to provide enough nutes to the plant and they pretty much stunt. The true leaves try to develop, however, they can't carry them through. Here is the original thread I started on it that went through a few recommendations, but once I thought I got it under control, it came back. So I will start with some photos:

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That is right before/during when they start to go. Before we start to pin it to "water", "light", etc. Here is what I have tried:

Water (Over, Under, and Contaminated). I hand watered the plugs, wait to water ONLY when at least 75% of the flats were dry, and I fill 5 gallon buckets with water and let them sit for at least 24-48 hours prior to heating up the water to about 80 degrees and bottom watering.

Light: I started with a 600w MH light, and I raised the light to about 4 feet and dropped it to 325w. Then I got a T5, hung it at 2 feet and only ran 4 of the 6 bulbs.

Ferts: Used an insignificant amount on a single flat and same issues run throughout so negligible.

Temps: Temp controlled grow tent at about 80 degrees and 160 CFM running 24/7 giving me about 55% RH.

Soil: Hoffman's for the first 2 flats, RR plugs for 2 flats, and most recently PROMIX BX.

Ok, now that I got that out of the way, here is the dilemma. I have ran through all of the checks, made tweaks, and just when I think I got the hang of it, nope, shit goes down hill. Most members talk about the purple Cotys are a result of the lights being too close, however, nobody has had leaf drop. I did extensive research on the web on this topic and found nothing on Marijuana sites, Garden sites, or Pepper sites that fits my issue at least 50/75%. Like I said, most have experienced purple leaves, but none have had leaf drop associated with it. What I did find was an article written talking about purpling and dropping of cotys in corn where the soil has blocked root development.

Just about the time I found that article I was noticing my cotys in the flat I planted last Saturday (10/11 Feb) in PROMIX looked much larger than the ones I planted weeks earlier.

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This one is from the previous planting in Hoffman's
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Although there is some purpling in the first photo, they still look MUCH healthier than anything that I have grown in the past 2 months. To be fair, this flat has spent 100% of its' life under the T5s, and the other flat spent about a week under the 350w MH. I even hung the T5 super high when I got it and the Hoffman's flat still purpled while the Promix flat got a little leggy. I have since dropped it to about 7/8 inches and am monitoring it every few hours.

What drives me crazy is the fact that there are plenty of growers here and elsewhere that use MH with little or no issues, and others use T5s with no issues. The last thing that I can think of is possibly the soil. I am skeptical of that because of the fact that many people swear by Hoffman's (AJ, BigCedar, etc) and it is hard to believe that when they are starting thousands of seeds with no issue that it doesn't work for me. A question would be what about a contaminated bag? Has anyone ever experienced that?

Anyways, on to the solution. As my last (hopefully) effort I planted 18 3oz cups with seeds from plants that I hope to plant out. 15 cups are Promix and 3 are Hoffman's. My thinking is if the Hoffman's cups show the same signs that I have been showing and the Promix doesn't, it is the soil, if they both grow with no issue, it was the week and change the Hoffman's flat spent under the MH before it got moved to the T5, and if nothing grows, then I am gonna go jump off a bridge....joking......kinda.....

But I am using this as more of a "Purple Cotyledon Leaf Drop" thread, instead of a HELP HELP HELP thread UNLESS you have experience with this issue. I would love to get your .02 if it isn't something that I have tried.

These are about 3-5 days old and are from the Promix flat
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And this is almost 3 weeks old in the Hoffman's mix. Since this photo, the leaves dropped and
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The saving grace is the fact that this is my first season and I will have many more to come. It would just be nice to get it right so the next time I do this I don't spend winter fighting plants and instead I can hang with the guys here on the boards..

Thanks for lookin.
 
Hey MGold. I gave a couple of my established plants to my girlfriend's Mom (she lives near Emerald Isle) the last time she was up to visit. A couple weeks ago she told me she was having a lot of trouble with leaf drop. I just figured she was either over fertilizing them, overwatering, or not getting enough light, but when I read your post I'm thinking maybe it's something with the water. For fun, I googled water pH for her area and although I didn't get a number I noticed that they have soft water. According to a website I found from Utah State University soft water contains sodium that can be harmful to germinating seeds. Maybe it can cause nutrient lock in seedlings too. I don't know if that's the case for you, but maybe it would be worth it to get some bottled water to try feeding some new seedlings with and see if you get a different result. Good luck man!
 
he said he was using distilled water MJG. Just thought I would point that out. That Hoffmans looks very compact/sunken and soggy when compared to the PRO MIX...which looks perfect. Also I would not do any nutes that early on. At least until the first two true leaves have been established.

Once one of the sprouts pops you should be leaving the top off permanently.
 
I used distilled water for a while, then I began using water left out for 2 days to get rid of chlorine. Not the best ph, but shouldn't kill it.

Spongey, I only water every 3 or so days (when the center cells of the tray look dry-ish on the top) and I watered yesterday. I bottom water, let it soak up for an hour or so and then dump the left over water in the flat. I am thinking if anything, I let em go a little longer to avoid it.

I agree that the Promix in the cells looks much better and the Hoffman's does look sunken. That has been a constant. I just find it hard to believe that the soil is bad when so many are having great success.

I am not planning on feeding until I pot them up when they have a good rootball. Also, the top is off on all the flats with seedlings.
 
I use the Hoffman's with great success. It is kind of fussy to hydrate--per AJ, put it dry into the container, then add water and let it sit for a few hours. Advised not to spoon it in 'wet' into the container due to compaction. Otherwise, it has worked very well and then its on to the ProMix for the next pot up.

If you are running a head to head test with Hoffman vs ProMix, it could indicate a bad batch--but when both your Rapid Rooters and Hoffmans went down last time, it showed something else going on.

Other than that, our grow area is different, so not much I can advise. I use an oscilatting fan a couple hours a day, and the area is only semi-enclosed. I use T8s and hang em 1-3 inches above the plant tops. The only time I got purpling was when I tried 24-hr lighting. The Trini Scorp Reds called foul after the first day, so I backed off to 18-6. No problem since.
 
You need to check the temp in the soil if possible. What it looks like to me is too wet and too warm. I deal with this issue every single year, yeah, I never learn...
 
I bottom water, let it soak up for an hour or so and then dump the left over water in the flat.

I let my trays soak for about 5 minutes each with the water level about 1/2 way up the cells. The top of the soil never looks soaking wet. I just strictly go by weight. When the trays are almost as light as new dry mix, I bottom water again for about 5 minutes. About every 2 or 3 days with ambient temp of 80F in my grow room. It sounds to me like you are watering way too much.
 
from your pics...they are definitely too wet. also, as mentioned before, if you have soft water, then sodium levels are too high and ph is off, this can def kill them. check for soft water, check the water and soil ph level, and def go easier on the water...pix show your trays are way too wet. no nutes needed until 1st true leaves start too emerge....good luck.
 
Soft water does not say anything about ph or sodium levels. Soft water means there is little Calcium and Magnesium (and the associated bicarbonate). Now if you have hard water and use a water softener, then the calcium and magnesium will be replaced with sodium.

And yes it looks like an overwatering problem.
 
I use the Hoffman's with great success. It is kind of fussy to hydrate--per AJ, put it dry into the container, then add water and let it sit for a few hours. Advised not to spoon it in 'wet' into the container due to compaction. Otherwise, it has worked very well and then its on to the ProMix for the next pot up.

If you are running a head to head test with Hoffman vs ProMix, it could indicate a bad batch--but when both your Rapid Rooters and Hoffmans went down last time, it showed something else going on.

I am with you 100%. I used that method in order to initially hydrate the soil and you are right with the Rapid Rooters. I was watering every night with the RR plugs by hand, and if it is an overwatering problem it would make sense.

You need to check the temp in the soil if possible. What it looks like to me is too wet and too warm. I deal with this issue every single year, yeah, I never learn...

The soil temps are about 70-77ish. I have a heat mat on em set to 84 until most of em pop up then I take it off so I dont overheat the soil. Yea, I am in the same boat, you need to tell me a dozen times before I get it right....

I let my trays soak for about 5 minutes each with the water level about 1/2 way up the cells. The top of the soil never looks soaking wet. I just strictly go by weight. When the trays are almost as light as new dry mix, I bottom water again for about 5 minutes. About every 2 or 3 days with ambient temp of 80F in my grow room. It sounds to me like you are watering way too much.

Hmm...I really never thought of that. I was under the impression that you water fully (by soaking the soil) and then wait until most of the cells dry out on top and then water again. I will give it a shot letting them go for a few minutes in the water rather than an hour....

from your pics...they are definitely too wet. also, as mentioned before, if you have soft water, then sodium levels are too high and ph is off, this can def kill them. check for soft water, check the water and soil ph level, and def go easier on the water...pix show your trays are way too wet. no nutes needed until 1st true leaves start too emerge....good luck.

I had the same issues with bottled water, so now with the new info from you guys I am leaning more towards overwatering.....

Soft water does not say anything about ph or sodium levels. Soft water means there is little Calcium and Magnesium (and the associated bicarbonate). Now if you have hard water and use a water softener, then the calcium and magnesium will be replaced with sodium. And yes it looks like an overwatering problem.

Another vote for overwatering.....


So as an aside, is it fair to say that the purpling and leaf drop are separate issues?? Where as, the purple leaves will not be an issue, however, when coupled with too much water then I run into the problems...

Thanks for everyone's responses.
 
hey Matt,

just saw this and after looking at everything I noticed I am in a similar boat.. besides the fact that I left for the weekend and about 8 of the seedlings that I planted in a 36 cell flat died (had about 25 or so pop up the first week or 2) and I soaked them right after, and besides the ones that got fried, the other ones are doing well..

I also have a few that were purpling so I moved the CFL lights up a little to about 5-6" and had only 2 of them on for now until they recovered, but now I have all 4 back on but still up higher, and switched them to the 20/4 cycle (but I think I am going to go back to 18/6 because it worked better I think with my previous batch) but anyways the purple plants are still slightly purple but are getting better..

as far as the watering I have been doing something similar to what you are where I see most of the tops of the cells looking dry and I bottom water them.. I notice that even though they look dry.. they really are not, that Hoffman's stuff really really holds onto water, it's crazy.. so I am going to start waiting until they look dry on the top.. and then wait like 2 days after that before watering.. and I will start feeling the weight also since it will give a better idea for when to water..

but anyways, some of the seedlings look a little like yours, where some are/were turning purple, but since i switched the cycle around they are doing much better as far as being purple, but now that the purple is going away I notice that they are yellowing a little.. so I am going to back off on the water for a while and let them dry out more before watering, and I probably won't soak them as much as I was before, so that the cells will be damp/moist but not soaking wet.. even though the top may still look a little dry.. at least before the water is completely absorbed..

hope this helps, and that you get things back in order.. I would just do as everyone else is saying, lay off on the water with the Hoffman's I was really surprised at how well that stuff holds water, and since I am not use to it.. I was tending to over water them
 
I am with you on the watering now. I really didn't think much about it because I figured, if the top looks dry, then it needs water. The thing is purple leaves (generally) don't equate to dropped green leaves. Overwatering does tho....

I am gonna go by weight AND sight from now on. I will probably let em start to droop a little and then let em sit in a warm water bath for about 5 minutes (like musky recommended) and that should make a difference. I am just keepin an eye on the tops of the plants and if they get TOO purple I will back the lights up a bit, but right now I brought the T5 from like 16 inches down to about 4 or 5 and they seem to be doing great. It is a battle between leggy/purple, but Ill take a bit of purple, they will grow out of it...
 
nice that's good, and yeah the purple is more just something to watch out for so they don't burn but they seem fine as you said, it's just crazy how much water the Hoffman's holds like I said before, and I just kind of realized it today and yesterday that I really need to let them dry out more.. they were ok before, but I think they were right on the edge of being over watered, and when they dried out over the weekend, I soaked them like crazy and they started yellowing a lot more lol.. oh well..

hopefully this fixes everything for you so you can get them going!
 
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