First week flowering and still plagued by new growth yellowing

This has been an ongoing problem for me for a long time.

As you can see in the pictures, what is happening is that ALL of the older growth is perfectly healthy and normal.

The problem is with the new growth ONLY. What is happening is that the is yellowing starts at the base of the leaf, and gets lighter and lighter until by the time you're at the tips it's green again.

Now, i have had heat problems most of the grow since i wasn't running an exhaust fan. I do have a fan going now (after i put that in, their growth rate almost doubled) and the ambient temperature is good i think. It sits stable at around 75f during the day and then it drops as low as 60f overnight (according to the mix/max on my temp guage).

Any drop of liquid that goes into the soil is pH tested and adjusted. I'm well aware of the importance of pH and i really don't think its a pH problem. To be honest what i suspect is maybe the light is too close to the canopy? The tips are generally between 45 - 55cm (17 - 21 inches) below my 600watt HPS.

Has anyone else had this problem? The only thing that makes me think it might not be the light too close is that i see this yellowing occuring on small growth tips well below the canopy - they are completed shaded yet show the same yellowing.

I'm guessing that you've switched to bloom fert already? I'm asking because it's a common mistake, and something that i don't hear mentioned here, as much as it should be. I used to make the same mistake too, and could never figure out why the hell my plants were mostly yellow by the 5th week, and most of the fan leaves kept falling off.lol Well, nobody ever told me that you were supposed to keep using veg fert until after the plant has gone through the stretching phase, during the first 1-3 weeks of 12/12. Now that i know that, I don't start the bloom fert til day 10-20(depending on what my plants tell me), and I haven't had the early yellowing problem, since. Also, when you switch to bloom fert, it's a good idea to keep alternating with the veg fert, periodically.(like every 2-3rd feeding)

Nope, i continue the vege ferts until the middle of week 2. There's no way this is a nitrogen deficiency because it is affecting the new growth only.

These are less than one week into flower anyway (actually, one week today).

this happens with most strains when you flick to flower i dont no wat its called but i fiind that the yellow spots become bud sites

Sorry bro, but I'm going to have to argue with ya about the nitrogen, because I'm 95+% sure that's what the problem is. My guess it that it's just starting to go into the stretching phase, was close to being deficient beforehand,(bot not visible yet) and now doesn't have the extra fuel needed to supply this vigorous growth spurt. That's why only the new growth is yellowing.

Also, I can tell you that your light isn't too close to cause problems, unless you're not running enough fans in the room. I also run a 600 HPS with an open reflector, and mine runs about 14" from the closest tops, without any problems.

Its' the nitrogen, I tell ya.lol

I appreciate your help, but i don't agree. Nitrogen is a mobile element which means it can move around the plant. If i had a nitrogen deficiency, then i would be seeing it in the older leaves first. If you can find anywhere which says that a nitrogen deficiency can make new growth yellow while leaving all older growth perfectly lush green then please give me a link! No offence - i do appreciate your help, i just know its not N. Further refuting this is the fact that i fed it a heavy feed 24 hours ago (veg nutes - high in N). I've had this problem the whole time. Check out this other post where i complained about it; https://www.rollitup.org/marijuana-plant-problems/315300-new-growth-yellowing.html (i just realise you posted on that thread too)

bloochedder said:

this happens with most strains when you flick to flower i dont no wat its called but i fiind that the yellow spots become bud sites

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I find it hard to beleive that this is normal. It will probably continue growing without any changes and i might even harvest a reasonable amount - but its not normal.

I'm pretty sure back then it was related to heat. I still am pretty sure its heat related especially after looking at this;
http://www.icmag.com/ic/showthread.php?t=11688

On that page, search for 'temprature changing' - you will find a pic very similar to mine. Maybe the drop to 60 overnight is too low?

^Nah, i already took the temps into consideration, and they're a-okay, as long as it doesn't get too much colder at night. Mine hover right about 60* also, and have been fine. But, I can see where that would be confusing, because the effects are just about identical looking.


Also, the " yellow budsite theory" isn't true, so, you're definitely being skeptical for a good reason.lol I can't say i've ever heard that one before.

http://www.amsterdammarijuanaseedbank.com/Growguides/Hydroponics/how-to-grow-marijuana-hydroponics-5.html
"Recent research has shown that night cycle temperatures are just as significant as day cycle temperatures in plant production and it is in fact the relationship between them that has most effect on the final shape and productivity of the plant. It is important to avoid large temperature fluctuations between the day and night cycles as this can lead to weak and poorly formed plants. It is ideal for most species to try and bring day and night temperatures
as close together as possible and this is not as difficult as it sounds."

Not sure exactly what this research is, but i've taken alot of sound advice from this site. The people seem to really know their shit.

Have a read of this too
http://www.cannabisculture.com/articles/1536.html


Maybe the fluctuations are too large.

Nizmo, This is exactly the problem I am having right now. Almost immediately after switching to 12/12 light, all new growth is yellow. After one week of 12/12, they are still yellow. I didn't know until reading this thread that I should be using veg nutes for the next 2 weeks, so I will switch back to the veg nutes. The 1000 watt lights are 12 to 15 inches away, and a thermometer set at the tops of the leaves shows temps between 70 and 85. After reading this thread, I am starting to think it may be heat/cold related. My lights are on all night, from 10 pm to 10 am. We had some cold nights (When my lights are ON) this week, perhaps it got too cold?

I think the important question here is this: Is this yellowing a problem? Does anything need to be done, and if so, what?

I fertilized a few pots last night with veg nutes. I will compare them to the pots I didn't fertilize. This morning, I really can't see any change.

Good luck, and please if you find a solution, let us know. I'll let you know what happens here.

Okay, I'm retracting my original diagnosis, and presenting a "new and improved" version,lol......instead of relying in my 'less than impressive' memory, I looked around a little, and think I found your problem. I'm pretty sure that you are starting to show symptoms of a sulphur deficiency, which effects the youngest leaves first, like your's. Check out the sulphur section, and see if you agree.... http://www.icmag.com/ic/showthread.php?t=11688

Also, check out the iron section too, because there are similarities. But, sulphur is a much better match, so I'm betting on that.

Thanks Jawbrodt. I'll try adding sulphur (epsom salts in water) tonight when the lights come on. My nutes (Sensi grow and sensi bloom) don't seem to have any sulphur. They do have iron, so I doubt if that is my problem. My soil, Foxfarm Ocean Forest, may or may not have any sulphur.

jawbrodt said:

Check out the sulphur section, and see if you agree.... http://www.icmag.com/ic/showthread.php?t=11688

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That page is great. Looking at that it may indeed be a sulphur deficiency...

Rando said:

Thanks Jawbrodt. I'll try adding sulphur (epsom salts in water) tonight when the lights come on.

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Has it helped with the problem? I'll give it a go tomorrow and report back in a day or two.

did this help the problem?

I had this same thing happen to me last week. All the yellow spots turned into beautiful baby buds. enjoy the magic

dadio161 said:

I had this same thing happen to me last week. All the yellow spots turned into beautiful baby buds. enjoy the magic

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That doesn't mean that this isn't a problem. If i left things as they are, i would still have no problem finishing the flowering phase. However, this is not normal and it will have a negative effect on the results - by how much is anyones guess, but i'm a perfectionist.

I'll be starting flowering nutes tomorrow (12 days into flower) so ill add a small amount of epsom salts to the mix and see what happens. I suspect i might have a slight magnesium deficiency aswell as the sulphur since the way they look aren't exactly "classic" examples of any particular deficiency. But they most closely resemble sulphur and mg - both of which are provided with epsom salts.

The yellowing has actually improved slightly (but noticably) by raising the lights and keeping the temperature warmer during the night cycle - but still not perfect.

The fert im using has 0.01% magnesium as sulphate and 0.008% as EDTA chelate. Im wondering if thats too low...

Is this really something i need to sort out?

I am still battling with temps, but i'm losing faith that this is temperature related.

I fed one of them yesterday with 1 teaspoon of epsom salts in 3 liters of water along with the flower nutes (first time using them). Today the yellowing on it looks to be worse (i dont have a picture for that - the picture is the plant still waiting to be watered)... I think i added too much epsom salts though.

I fed the rest of them with the same, except instead of 1 teaspoon i just used a large pinch of the epsom salts. Will see if there's any improvement tomorrow...

My problem appears to be solved. I had very yellow new growth during the first week of flowering. My problem, which looks similar to yours, may have been caused by a different set of circumstances.

I tried epsom salts and 2 pots, miracle gro on 3 pots, and Sensi bloom A and B on 2 other pots. I saw no change from any of these.

What seemed to work was moving the lights further away from the plants, and switching my light cycle so that the lights are on during the day and lights are off at night (instead of visa versa). The reason I switched is we had some warm days and very cold nights, which meant that my room temperature was colder during my lights on cycle, and warmer during my lights off cycle.

In any case, the problem seems to be solved. I have nice green plants with nice young buds after 2 weeks of 12 hour days.

Rando said:

I tried epsom salts and 2 pots, miracle gro on 3 pots, and Sensi bloom A and B on 2 other pots. I saw no change from any of these.

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Yeah epsom salts appeared to do nothing to resolve my problem either.

I have finally sorted out my night temperatures, so that the night temp is only a few degrees lower than the day temp. This seems to be helping (but i still haven't got it 100% right - it's difficult to find the right setting on the heater so that it doesnt get too hot or too cold). I may need to invest in a proper digital thermostat.

Rando said:

switching my light cycle so that the lights are on during the day and lights are off at night (instead of visa versa). The reason I switched is we had some warm days and very cold nights, which meant that my room temperature was colder during my lights on cycle, and warmer during my lights off cycle.

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Aren't you now going to have the problem with too much heat during lights on then? Wouldn't you have been better keeping them off during the hot period and then having the lights on during the cold period and adding a heater if it wasnt heating enough on its own?

An update for this problem can be found on page 1 of my grow log; https://www.rollitup.org/grow-journals/329568-3rd-grow-unknown-strain-soil.html