3 wks into flower, yellowing leaves

I usually don't check in soil. My tap water here is terrible 530 ppm and 8 ph. I bought an ro water system and been doing lots of tests with my tds meter and thought I would try. I did it by running plain ro water and testing the runoff. I ran a little more water than normal so I would have good runoff and not such a concentrated sample. First test showed around 1900 ppm on both my plants one being a little higher. Flushed after I saw that and took readings to monitor how fast it was dropping per gallon of water. I want to say if your over 1200 ppm at this point it is building up salts and you need to be careful. I got mine back down and started feeding again and my runoff is around 900 ppm now and I am in day 42 of flower. It seems like my bud development has been slightly stunted and just starting to fill out more again. I also started adding blackstrap to the watering. I was worried about flushing and losing some of the good bacteria in the soil but new I had build up of salts at that point. I also noticed before this started happening my middle growth was very green. Almost too green thinking maybe it got to much N at some point? I switched up my ferts this grow too so maybe didn't have a good handle on everything.

How many watt light are you using? I remember you said you keep it 4-5 inches above the plant. Even a 250 could do some bleaching at that distance.

Oh yes, fungal gnats it is then. Put some cut potatoes on them, problem solved. Ha!

For anyone interested in following the life of a pot plant, just expect to start losing leaves once they enter flowering stage. They will continue to shed leaves until the day you harvest. Not a problem, just how it works.

Alexander Supertramp said:

Simply not true in the real world. Only true in forum land where people blame the plant instead of their lack of growing skills....
Plant yellow and die after they have finished fruiting/flowering, not during.

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OK, you win, I have no experience in this after 34 years of growing pot. And I have no growing skills, you are AGAIN correct. I am crawling back to my corner and will await your words of wisdom as to the life cycle of the marijuana plant. Not sure what I should do next, but I guess if I'm getting yellow leaves during flowering cycle I'm fucking up really bad.

That never happens to real growers like yourself whose leaves are a vibrant green until the day of harvest. I aspire to reach your level of botanical knowledge, and the application of such expertise.

Today's pics of my plants (sig line) show a lot of color loss as they are toward the end of their life.

hbbum said:

Thanks, I suspect it could be fungal gnats (dammit). I have not seen them in my actual grow room, but I did notice a bug in the adjoining room that when put under my scope looks a lot like a fungal gnat.

I will hang a strip in my room and see if I come out with a bunch.

Thanks for the quick replies

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It won't be fungus gnats because their larvae munch on roots and they usually can't hurt an adult plant. Also if you had them you would know for sure because there are swarms usually of those nasty things.

It is a 400. I decided to bite the bullet and pull her out and do a proper flush. I ran the hose through the pot for a bit until water cleared out. Then I ran a couple of gallons on PHd water until I got my run off to 6.8 then put about a liter of water with nutes in it.

Cleaned up some of the dead leaves on the very bottom of the plant and did some canopy management. I was not able to get my screen back in, was worried I had already done enough man handling for one session and was able to get a lot of the tops pushed up into the canopy that previously did not get much light.

I got some great pics while out, going to load them up into my journal thread.

Thanks AimAim, I appreciate any insight. From what I was seeing the yellowing seemed odd because it was fairly early in the flowering stage. Have ruled out the fungus gnats since here are just none in the grow room.

As I mentioned above, I decided to do a water flush since I figured it couldn't hurt much as long as I re-fed. chance to pull the plant out and get a better look. I still dont know if I actually have a problem or if it is just natural or light bleaching. I have moved my light up a little, but it is still pretty close ~8in from the top, this gives me better coverage of the entire plant anyway and it keeps the bottom of the growth at about 20" from the light so I should be getting good light penetration.

A 400 watt hps light should be approx/at least 15 or so inches away from the top.
If you have half that, and its a hps, then the leafs could be bleaching from the light burn.

The yellow leaves thing can be quite the debate. I have friends that swear that most should be yellow and dying before harvest to ensure that bad tasting N is all out of there. lol But I know a lot of old school growers with lots of outdoor experience here say keep it green all the way through. I find it quite hard to keep it green until harvest but I do try to minimize yellowing with proper feeding and using a completed food that does not cut out all the N and spike the P and K...maybe a bloom booster (snake oil) here and there. Sometimes you just have a feel for the plant and know something is not right. I found myself in the same situation this grow and as much as I try to avoid flushing sometimes it is the best way to approach it instead of guessing and over feeding and locking other stuff out....hate playing that game. Aim Aim, I just checked your grow and it is looking good....you have done a great job of keeping them green! I run a 400 as well and try to keep them 12-15 inches....sometimes you have to test the tolerance of the plant I noticed when I was in that 8-10" range and backed off my plants would respond and seem more healthy then when I would get the light right on them...

Something that might work well for you now HBbum is getting a tomato plant ring or support now and fitting it around your plant for support and it can open up the middle for you a bit....

AimAim said:

OK, you win, I have no experience in this after 34 years of growing pot. And I have no growing skills, you are AGAIN correct. I am crawling back to my corner and will await your words of wisdom as to the life cycle of the marijuana plant. Not sure what I should do next, but I guess if I'm getting yellow leaves during flowering cycle I'm fucking up really bad.

That never happens to real growers like yourself whose leaves are a vibrant green until the day of harvest. I aspire to reach your level of botanical knowledge, and the application of such expertise.

Today's pics of my plants (sig line) show a lot of color loss as they are toward the end of their life.

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because you dont know anything at all, MJ senses your feelings about harvesting it and turn yellow in mean time till you cut it down.
before that feeling emerges, it should be still green.
leaves turn yellow in flowering?? whatta lot of crap

Thanks, here is after going back in the box.


I may go get one of those short tomato rings to see if it can help me pull some of the lower bud sites up to the canopy.

I notice that the main yellowing seems to be concentrated in the center right below the bulb. I am almost certain that the discoloring was caused by light bleaching. And it seems you have taken the right steps and didnt panic and take drastic measures. Nice job cause your plants look great other than the slight bleaching.

Thanks, I was a little hesitant to do the flush but I figured even if salt build up was not an issue, it wouldn't hurt to do a flush. I raised the lights up to 12" above the yop of the canopy:


It seems really high, but the good news is the plants seem healthy after the flush. I will be giving them some nutes on the next watering and will continue alternating nutes/water+molasses.

Thanks everyone for the advice and guidance.

No need for the molasses. Plants make their own carbs and lack the ability to uptake them through their roots. Save the molasses for when your brewing a tea and trying to jump start some microbes. Using it as a drench only introduces calcium among other things into the medium that is not available to the plant. Nor will ever really become available. So it will just set there and build up very possibly inhibiting the uptake of other nutrients, mainly nitrogen.

AimAim said:

Oh yes, fungal gnats it is then. Put some cut potatoes on them, problem solved. Ha!

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Here ya go Mr. Ha...
http://www.helpfulgardener.com/forum/viewtopic.php?t=24671

For anyone interested in following the life of a pot plant, just expect to start losing leaves once they enter flowering stage. They will continue to shed leaves until the day you harvest. Not a problem, just how it works.

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You are correct...because...they are deficient and lack the proper diet. Keep feeding them high P and low N food during flower and you can count on this happening. It has zip too do with a plants natural life cycle. Yes you will lose a fan here and there. You may want to study up on 'sink leaves and source leaves'.

I went to get a tomato ring and i found this one at HD that seemed like it would do the trick. Hopefully I didn't stress the plant to much with the man handling to get the but sites organized in the canopy. I have done a little each day to try to minimize it. I also cut out about a dozen anemic looking brances along the bottom that had not been getting much light and had tiny bud sites with very light green coloring.
View attachment 2660801

The coloring has not gotten worse, I will continue to keep an eye out to make sure the raised lights resolved the issue.

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I am thinking I will keep the molasses once a week in the watering just to keep the soil healthy. I have been using a little less that 1Tbsp per gallon and apart for what is hopefully just bleaching things have been going well.

Plants look great, very nice job. You may want to think about doing a EWC tea w/molasses once a week or so to get the best benefits.

The bloom food does not have enough n to keep up foliage...use the grow nutes and throw the high p bloom nutes in the garbage

Sometimes 1 teaspoon of epsom salts per gal. of water will help that problem. It will either work or not. But it won't hurt your plants either way !