3-4 weeks in to flowering my fan leaves are starting to yellow very fast

Hello all I am having some trouble with my ladys and was hoping someone here could give me some advice on what is causing it and possibly what to do next. First I will try and list as many of the specifics what whats my setup is.
1000 HPS on moving track
Ocean Forest Soil 3 gal pots
GH Flora series with CalMag, Floralicious Plus, all PHed to 6.3-6.4; My runoff comes out to be about what I put in.
I hand water measured amounts and feed nutes every other watering.

I am 4 weeks in to flowering and early on in my 3rd week I noticed some yellowing on the fan leaves in the middle of the plant and within days it had spread more to the point where I knew this isnt just normal yellowing, I actually have a problem. I have 5 plants and It is only happening on one of them but today I noticed that another one is starting to do the same thing, yellowing in the middle of the plant. I was suspeced N def. and gave them a boost in that as I never compleatly cut that out of the feeding. But I dont really see signs of improvement. I doubt it would be a Mag. def. as I have been giving them calmag. I flushed the one girl today with tap phed water. But now I am at a point where I dont know what to do next. If anyone has suggestions im very open to hear what you have to say.

Causes :

1) Undernuting ie Your babies are hungry ! Especially at this time in early flowering when they are burning through nitrogen like crazy.

Also undernuting of P and K would make the plant suck it's nutrients from the leaves since there none in the soil..Do you have reddish stems ? Any weird greyish spots along leaf edge..splotches ?

Yellowing leaves, red stems, slowing growth are all signs of N P K deficient.

2) Rootbound

3) PH off ....causing all kinda of nute problems ( I noticed the folded under leaves... along the edge )

4) Too low RH

5) Overwatering.

I'm going through a slight early yellowing but I know it's from underfeeding as I always err on this side of caution.

Some yellowing is natural but this is kinda early and you don't have much leaf left as is.

Good luck I hope you fix it fast. ... real fast...running out of leaf there. they will not turn green again but you can stop it from getting worse.

My bet is undernuting or PH / nute problem.,,,under nuting, I don't see tip burn. so your not over dosing them.

FYI There is a sticky at the top...but I'm stoned and bored so I'll regurgitate it here.

Under nuting....10 to 1

Edit :

Now that I look at it....sure it's not root bound ?

purple stem- phosphorous deficiency
overall yellowing- nitrogen deficiency

you need more nutes. people starve their plants more often than ever during flowering.

I'm going through seemingly the exact same problem. I've tried flushing and after giving a stronger dose of bloom nutes about two weeks later to no avail. Out of about 20 plants if seems to be effecting about 15 of them. Lucky me. Are you growing different strains?

might be helpful to check out my thread and see if any of the advice people gave to me might pertain to your grow
https://www.rollitup.org/marijuana-plant-problems/590580-dying-yellow-leaves-month-into.html

I was going by the GH feeding chart for soil and I guess I need to be more aggressive with the nutes.

Thank you all for the replies and I will be keeping this updated. I am going to give them a stronger dose of nutes and see if I see any improvement.

Just keeping this thread updated, Gave the ladys a heavy dose of nutes and I dont see any signs of improvement but also I dont see it getting much worse. I thought of the possibility of it being root bound and I transplanted into 5 gal pots just now. It didn't seem like they were rootbound from the looks of it when i pulled it out of the pot. On the side of caution and experimentation I transferred it anyways. I will report back in a few days with my results. Just to reiterate this is only happening to one of my 5 plants. Also another side note. I noticed that the fan leaves stems are starting to turn redish color. Is this a P def?

jackamofo said:

Just keeping this thread updated, Gave the ladys a heavy dose of nutes and I dont see any signs of improvement but also I dont see it getting much worse. I thought of the possibility of it being root bound and I transplanted into 5 gal pots just now. It didn't seem like they were rootbound from the looks of it when i pulled it out of the pot. On the side of caution and experimentation I transferred it anyways. I will report back in a few days with my results. Just to reiterate this is only happening to one of my 5 plants. Also another side note. I noticed that the fan leaves stems are starting to turn redish color. Is this a P def?

Click to expand...

YES! its a P def. Happens more often than people think. Yellow leaves usually wont get much better but you can stop further damage. Maybe a light flush followed by a dose of bloom nutes. A dose of compost tea would help as well.
Low temps can lockout P.....plants nearest the A/C often show P def symptoms. Higher EC's with relatively low P levels can cause salt uptake when the plant wants P. Down drooping leaves will also be a symptom of high EC. If leaves are krinkled, twisted and distorted, especially the tips/margins then you should consider salts as an issue as well. If simple loss of color without necrotic tissue then likely P def vs P toxicity/salt uptake. Make sense? Peace.

Excess water soluble N during bloom will cause stretching as well as something I call "cabbage leaf" or "lettuce leaf".....the leaves growing at the tip of the kola become rounded and distorted as if the plant is trying to re generate back to veg. We've all seen those leaves..............

Transplanting will have little benefit at this point due to the plants emphasis on fruiting vs root production. Peace.

Yes it makes sense, thank you for the input GK1! I already flushed her 3 days ago and gave her a feeding yesterday. It is very strange that it is only happening to one of the 5. They are all getting the same nutes, light, temp and yet only one of them is affected. This is why I was thinking root bound? What are the possible problems that would only effect one? The plant in question is actually in the middle of the room and the one that is closest to the air vent is doing just fine. My temps are on the higher side if anything being in FL. They are usually at 77 to 80 degrees stable during the day and at night they go down to about 70 to 75 degrees

Also another important question I have been going back and forth about in my head. To up the dose of nutes should I

A: feed nutes that are the same strength as they have been every time I water instead of watering with plain water in between feedings

B: Make my nutes 1/2 times stronger and water in between with plain water as I have been doing.

Thanks guys I really appreciate the input it helps me not drive my self crazy thinking about it alone.

I don't know about GH Flora... but I would give them a nice balanced full strength feed and see how they react... something like 7-9-5 or 10-10-10.

The downward droop to the leaves indicates a slightly high overall EC while the yellowing indicates a def of P. Only one plant? Then I'd use it as a laboratory and have some fun and maybe learn something too......
Its tough to know if you flushed enough without a meter but you must be careful with your recent transplant....no roots in new media and the excess water can lead to root rot.....BE CAREFUL. I wont say that again. Wait, yes I will. BE CAREFUL. Mix up your normal bloom mix and water. Again, without a meter its hard to say if what your doing is enough. In soil i assume you're watering about twice a week? You'd need a relatively strong nute mix as opposed to a coco guy that waters everyday delivering nutes. Make sense?

If you see an improvement or yellowing is stopped then you should up the P on the other plants as well. They cant be far behind.

Thanks for the heads up on the root rot, something I didn't even think about. I usually water every other day but I always do the pot lift to see if the need it or not. Is there a good EC meter you could recommend? by the sounds of it, it would be a good investment.
Shes not really showing much sign of improvement but then again the results are not instantaneous with these matters. You are also right about my other girls not to far behind, I noticed redding of the fan leaf stems in one of the other ones. I already upped the does of nutes to all of them so hopefully I am solving the problem before it really starts to take effect this time. It is all a learning experience and I will just use every thing this time around to make sure it doesn't happen the next time around. These ladys are all bag seed so I dont know anything about the genetics but I wanted to grow these all the way through before I used my actual good genetic seeds. I have some Heavyweight "Fruit Punch" and some AK48 growing in my veg room so when these ladys are done I will just pop them in the flower room. Thank you all for the input!

jackamofo said:

Also another important question I have been going back and forth about in my head. To up the dose of nutes should I

A: feed nutes that are the same strength as they have been every time I water instead of watering with plain water in between feedings

B: Make my nutes 1/2 times stronger and water in between with plain water as I have been doing.

Thanks guys I really appreciate the input it helps me not drive my self crazy thinking about it alone.

Click to expand...

I do either, depending what kind of mood I'm in, and I don't seem to see a difference.
Sometimes I just add more when I water, but if I think of it after the fact, I will feed every water.
I wouldn't necessarily go 1.5 times the recommended (what you are using now), but maybe a quarter.
I use powdered nutes, so instead of 1 scoop, I do one heaping scoop.

PM, I am not gauranteeing it. Spray ur faoliage with neem oil($10). Good for the foliage, wont hurt ur flower, and will kill anything on ur leaf. I spray neem oil on my plants in flower once a week, all plants have mold, we just keep it down with different methods. This is why Jorge suggest the h2o2 bath. I always keep a spray bottle of neem oil around. It stores forever, I spray with lights on, better off though.

So just an update, She is not looking worse so I think I have effectivly stopped the yellowing. I am pretty sure I was just underfeeding them. I am a little concerned about the redding of the fan leaf stems. Is this something that will go back to being green or is it something like the yellowing that once its set in theres no reversing it. Here is a picture of it.

How are they doing? Do you still suspect it was underfeeding?

The Hanna "black" meter is really sweet. Hope they're looking better!

some seem to keep the veg nutes for the first few weeks of flower. i would also add 1 to 2 tsp of epsom salts to a glass of warn water to mix, then add to gal of water. give em this, with a bit of n. the epsom salt is just mg. without mg, a plant cannot use other nutes. and they go thru mg. i use soil, and currently ghp flora nova two, including the kool blooms. but i dont use that last one, till buds are like end of your pinky size. a good dose of "bulldog", ie = epson salts, is an easy, pick em up.