yellow tops on 1st day of flowering???

Just prior to flowering I threw my girls from 24/0 lighting to 12/12 by first putting her in dark for 36 hours. When the lights came on after 36 hours of darkness, many leaves on the tops (of all plants) were yellow and lacked chlorophyll. It looks like a Nitrogen deficiency, even though I know it isn't. I'm guessing one of two possibilities:
1) Can this be due to a lack of light for 36 hours where the plant could not go through photosynthesis? Or,
2) Is there an element (in excess) that is used during the dark cycle that has now become nutrient deficient? This leads me to the other possibilities such as Iron, Sulfur, or maybe a Zinc deficiency?

Thank you!

It sounds like possibly a Magnesium deficiency. Is there any darker spots that are turning grey?
If so then it could also be maybe a potassium deficiency.

Wlecome to RIU
What nutes you been giving it
what soil is in it
how ofter do you water
and pics would be the best help.

I have a couple of plants in FFOF soil with a balanced pH of 6.5 (runoff). I also have a couple of plants in hydro (ebb&flow) with a pH of 5.9. I use Technaflora RFS for my salts. My soil watering schedule is defnitely under control (I use a spreadsheet and the works to track the progress of the plant). Hydro is 4x/day and I flood for 15 mins. I use air stones as well. All of the plants did it (soil and hydro) which points to a shared resource. Light?

It is looking better (except one plant), but I also changed my reservoir and the lights are 12/12. What about the reservoir being 12 days old and the plants not having light for 36 hours prior to the first day of Fall? I don't know.

when lights are off for an extended period of time plant uses stored food basically cannibalizes, so yes it is a nute deficiency, and was likely deficient before you put her in the dark, hit her with a little nitro and som bloom nutes and she'll be good bro.

svchop889 said:

when lights are off for an extended period of time plant uses stored food basically cannibalizes, so yes it is a nute deficiency, and was likely deficient before you put her in the dark, hit her with a little nitro and som bloom nutes and she'll be good bro.

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What he said.
Go little on the nitro your ratio needs to be higher in P and K than N

MendelMaster said:

Just prior to flowering I threw my girls from 24/0 lighting to 12/12 by first putting her in dark for 36 hours. When the lights came on after 36 hours of darkness, many leaves on the tops (of all plants) were yellow and lacked chlorophyll. It looks like a Nitrogen deficiency, even though I know it isn't. I'm guessing one of two possibilities:
1) Can this be due to a lack of light for 36 hours where the plant could not go through photosynthesis? Or,
2) Is there an element (in excess) that is used during the dark cycle that has now become nutrient deficient? This leads me to the other possibilities such as Iron, Sulfur, or maybe a Zinc deficiency?

Thank you!

Click to expand...

Doubt you actually have a problem, got pics? It is completely normal for a newly flowering plant to look a bit yellow right at the tips because the plant's energy is transitioning to a different focus, flower development. If this were my plant I would do nothing untill someone confirms that it actually has an issue. Post pics so we can see the problem, much better to hand out a solution if we see the problem.

Yeah def post pics for reliable help.

brasmith said:

Doubt you actually have a problem, got pics? It is completely normal for a newly flowering plant to look a bit yellow right at the tips because the plant's energy is transitioning to a different focus, flower development. If this were my plant I would do nothing untill someone confirms that it actually has an issue. Post pics so we can see the problem, much better to hand out a solution if we see the problem.

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That's not normal at all. Leaves shouldn't be changing any type of color the first couple weeks of flowering.

Mysticlown150 said:

That's not normal at all. Leaves shouldn't be changing any type of color the first couple weeks of flowering.

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Yeah they sure do.
Specially if your lacking in N

Just lets see if he post some pics, we will see then

Phenom420 said:

Yeah they sure do.
Specially if your lacking in N

Just lets see if he post some pics, we will see then

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Thanks Phenom for the backing. I'm often not too sure how to come back to things said with so much conviction.

brasmith said:

Thanks Phenom for the backing. I'm often not too sure how to come back to things said with so much conviction.

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Ah no problem
well some plp may never see that if theygave them plenty of N during veg or if their flower nutes have some N in it like say FoxFarm Tiger Bloom.

Alll my grows did that from lack of N my newer ones shouldnt since I got better nutes and a little more know how to use em.

Never really sent my plants into flower low on N but I do always notice a slight lightening of green right where the tiney leaves bunch when they are making their hairs, only in the very beggining though. I have seen on nearly everyones plants especially at the moment the plants transitions from veg to flower. After that though all goes away.
Thanx again

brasmith said:

Never really sent my plants into flower low on N but I do always notice a slight lightening of green right where the tiney leaves bunch when they are making their hairs, only in the very beggining though. I have seen on nearly everyones plants especially at the moment the plants transitions from veg to flower. After that though all goes away.
Thanx again

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Yeah well I started on not so great stuff so my plants were usually lacking something, N was one thing.

No prob man, love sharing the help I was given n here

Great replies, thank you! I think it was a Nitrogen deficiency coupled with a lack of sunlight for 36 hours.

So my question is:
Is there an unusual amount of Nitrogen used when the light switch goes to flowering? I'm thinking if you have a slight deficiency before you kick into flowering, then the results will be compounded. Maybe?

I tried taking pics but it was very difficult to see the lighter tops. Basically all the top meristems were a very light chlorotic green on day 1 and now they look normal. I needed to water and I also changed the reservoir, which helped the situation (I think). Unless it was going to rebound on its own, which is very possible.

MendelMaster said:

Great replies, thank you! I think it was a Nitrogen deficiency coupled with a lack of sunlight for 36 hours.

So my question is:
Is there an unusual amount of Nitrogen used when the light switch goes to flowering? I'm thinking if you have a slight deficiency before you kick into flowering, then the results will be compounded. Maybe?

I tried taking pics but it was very difficult to see the lighter tops. Basically all the top meristems were a very light chlorotic green on day 1 and now they look normal. I needed to water and I also changed the reservoir, which helped the situation (I think). Unless it was going to rebound on its own, which is very possible.

Click to expand...

Hey
Really 36hrs they should b fine without light and that really wouldn't cause the yellowing, they may fellow also because of the lack of light to lower limbs, so that would make it normal, but I would just boost em with a LITTLE N, keep the N ratio below the P and K.

We are talkin just a little bump not a big slamm of N.

The damaged leves wont get better but the others won't be affected.

Usually my deficiency shows around 3-5 week.
Some that got about 0 direct light went sooner possibly can't remember.

Damn im stoned this morning, YAY!