Yellow patches spreading mainly on top leaves

[Bibo2222]

Hello amazing forum.

Strain: probably sinai strain (got it from a bag of seeds)
Stage: 2nd week of flowering
Growing indoor
Growing in soil (premixed soil with added amendments at the beginning of the grow, then now using a bloom npk with 4-8-7 ratio along side calmag)
Tent is 2x2
Light :300w HPS
Room temp: 71 F to 79 F with RH 40% to 55%
No pests
Watering every 2 to 3 days with 6.5 PH tap water
Last water runoff PH is 7

As the title says, starting from the 2nd week of flowering i started noticing these symptoms right after i transplanted her to a 10 gallons pot. These symptoms appears to be spreading slowly now (just fed her 2 days ago) but i want to completely fix it and I'm not sure whether it:
Calcium deficiency
Phosphorus deficiency (I've read it appears on older leaves first, while here it's mostly the top leaves)
Or it's just of PH fluctuations ( just got an accurate ph pen a week ago)

A clueless new grower who is still learning here guys, and i would really appreciates some help

 

[Weaselcracker]

I think that’d be mainly calcium def you’re seeing. Sometimes it’s just part of overall underfeeding. Your plants don’t look severely underfed but symptoms have to start somewhere. Other times it’s part of a lockout due to other elements being too high, such as potassium. I’m not a deficiency guy really - @Emilya is pretty on top of the calcium def thing. Also post more info on your soil if you have it. GL.

 

[Emilya Green]

Hi @Bibo2222 and welcome to the forum!
yes, I am thinking Ca and maybe P ... it doesn't look like a simple deficiency and you are already giving calmag, and that to me says the cause is pH. One thing you said that makes me think you are doing the pH wrong is that you mention pH adjusted water, but not pH adjusted water/nutes. You should mix all of your nutes into the water first and then adjust your pH to 6.3 before applying it to the soil... not 6.5 pH. When you water the next time with plain water, also adjust it to 6.3 pH. Typically acidic nutes will drive the pH of your water way down into the hydro range in the 5's somewhere... and this is what you were giving to your plants. If this is what is happening here, it is no wonder there are lockouts.

Pay no attention to your runoff pH, it is totally useless to take that measurement in soil and whatever value you get is totally meaningless and depending on if you measure runoff at 2%, 10% or 20% runoff, the measurements will all be different. At what random point can you say that the runoff pH has ANYTHING to do with the pH of the soil above or the fluids you put in at the top? Your guess is as good as mine.
I think if you start correctly pH adjusting your incoming fluids, the lockouts will stop happening.

 

[Bibo2222]

I think that’d be mainly calcium def you’re seeing. Sometimes it’s just part of overall underfeeding. Your plants don’t look severely underfed but symptoms have to start somewhere. Other times it’s part of a lockout due to other elements being too high, such as potassium. I’m not a deficiency guy really - @Emilya is pretty on top of the calcium def thing. Also post more info on your soil if you have it. GL.

Thanks alot for your reply bro.
Sure here's the info on the soil (it's not very detailed i guess but it's the only somewhat decent soil i could get)
Ingredients :cocopeat-perlite-compost-vermiculite-humic acid
Organic matter: 75% to 80%
PH value: 5.9 to 6.3
TDS: 350-500 ppm
I hope this piece of info helps

 

[Bibo2222]

Hi @Bibo2222 and welcome to the forum!
yes, I am thinking Ca and maybe P ... it doesn't look like a simple deficiency and you are already giving calmag, and that to me says the cause is pH. One thing you said that makes me think you are doing the pH wrong is that you mention pH adjusted water, but not pH adjusted water/nutes. You should mix all of your nutes into the water first and then adjust your pH to 6.3 before applying it to the soil... not 6.5 pH. When you water the next time with plain water, also adjust it to 6.3 pH. Typically acidic nutes will drive the pH of your water way down into the hydro range in the 5's somewhere... and this is what you were giving to your plants. If this is what is happening here, it is no wonder there are lockouts.

Pay no attention to your runoff pH, it is totally useless to take that measurement in soil and whatever value you get is totally meaningless and depending on if you measure runoff at 2%, 10% or 20% runoff, the measurements will all be different. At what random point can you say that the runoff pH has ANYTHING to do with the pH of the soil above or the fluids you put in at the top? Your guess is as good as mine.
I think if you start correctly pH adjusting your incoming fluids, the lockouts will stop happening.

Hello Emilya
So first of all i can't thank you enough for this.
So the rule of thumb here is to keep the water at 6.3 whether it's mixed with nutes or just plain water. Got that part, but if you may, i would like to ask some questions just to get everything right from now on.
1- based on these deficiencies, should i increase the frequency of watering with nutes or should i keep it 2 plain waterings and 1 with nutes (nutes every third watering)
2 - how often should i add the calmag in this case and is it ok to mix it with my bloom NPK and give both of them in one watering session

Again I can't thank you enough for your help!!

 

[Canuckush]

Sounds like a coco medium rather than a soil medium. In coco you should ph at 5.8.

 

[Bibo2222]

Sounds like a coco medium rather than a soil medium. In coco you should ph at 5.8.

Hello canuckush, Do you think flushing and starting feeding at the correct ph would help or should i continue normal watering till it adjusts itself?

 

[Canuckush]

Hello canuckush, Do you think flushing and starting feeding at the correct ph would help or should i continue normal watering till it adjusts itself?

Just adjust the ph of the nutrients feed and keep feeding daily, see how she is in a week.
What nutrients are you using?

 

[Bibo2222]

Just adjust the ph of the nutrients feed and keep feeding daily, see how she is in a week.
What nutrients are you using?

I'm not from around here so i can't post a brand name or anything beneficial but i could translate the concentrations written on my NPK bottle
Nitrogen 4%
Phosphorus 8%
Potassium 7%
Magnesium 2%
Sulfur 2%
Silicon 0.02%
Copper 0.01 %
Boron 0.01%
Zinc 0.01%
Manganese 0.03%
Iron 0.1%
Cobalt 0.002%
Molybdenum 0.003%

The written dose on the label is 3ml per gallon of water

Edit: forgot to add my calmag label

Calcium 3%
Nitrogen 4%
Magnesium 1.5%
Boron 0.01%

With recommended dose of 1.5ml per gallon of water



And I was afraid to feed often so i wouldn't burn her (my first grow and still learning alot along the way)

 

[Emilya Green]

Hello Emilya
So first of all i can't thank you enough for this.
So the rule of thumb here is to keep the water at 6.3 whether it's mixed with nutes or just plain water. Got that part, but if you may, i would like to ask some questions just to get everything right from now on.
1- based on these deficiencies, should i increase the frequency of watering with nutes or should i keep it 2 plain waterings and 1 with nutes (nutes every third watering)
2 - how often should i add the calmag in this case and is it ok to mix it with my bloom NPK and give both of them in one watering session

Again I can't thank you enough for your help!!

I would increase the frequency of your feedings by going feed/water/feed/water and make the pH adjustments that we talked about. This should solve the deficiency problem, and then we can see how well your plant is responding to the nutes. Treat the calmag as just another nute and mix it in with the rest, all pH adjusted together. I am just not convinced that you need the calmag right now or whether the entire problem was pH related. I suggest skipping the calmag this time, adjust pH correctly and lets see what happens.

 

[Emilya Green]

also, lets confirm that you are dealing with a potting soil, and not an artificial medium such as something that is 70% coco and peat. It is ok to have peat and coco in there, but not as the major components, or our pH recommendations to you are all wrong.

 

[Bibo2222]

also, lets confirm that you are dealing with a potting soil, and not an artificial medium such as something that is 70% coco and peat. It is ok to have peat and coco in there, but not as the major components, or our pH recommendations to you are all wrong.

Again i can't thank you enough for your patience and help.

For the medium, it consists of this mixture (cocopeat-perlite-compost-vermiculite-humic acid) with ph 5.9 to 6.3, so i believe it's an artifical medium then with a different ph recommendation now, right???

(sorry for the confusion regarding thid point)
And I'll definitely follow your feeding advice.

 

[Emilya Green]

well, the compost and humic acid says to me that it is a soil, and not a soilless medium, but it is pH'ed as if it were to be used as a hydro system, so it is a little confusing. In your research have you found anyone else using this soil who has a pH recommendation? I would tend to think that with the ingredients listed in the order that they are, that this is a mostly coco/peat mixture, and should be run as such, as a hydro system in the 5.5-6.1 range.

With the base pH set to the high end of the hydro range, I bet you get a strong upward drift as the nutes are used up and the system reverts to the base pH of the medium and that of water. I bet you could come in low at 5.6 or 5.7 and then drift each time up to 6.1 or so... but it would also depend on how you want to run this stuff.
If you want to run it like you would a soil and let it dry out between waterings, come in with the pH low and let it drift upward. If you want to run more like a hydro operation (recommended) and water at least every day with aerated water, I would set the pH to 5.8 most of the time and once in a while give them a shot of 5.5 just to pick up the heavy stuff at the bottom of the range.

 

[Emilya Green]

Pay no attention to your runoff pH, it is totally useless to take that measurement in soil and whatever value you get is totally meaningless and depending on if you measure runoff at 2%, 10% or 20% runoff, the measurements will all be different. At what random point can you say that the runoff pH has ANYTHING to do with the pH of the soil above or the fluids you put in at the top? Your guess is as good as mine.
I think if you start correctly pH adjusting your incoming fluids, the lockouts will stop happening.

This whole last post was wrong, now looking more clearly at the medium and its needs, but I especially wanted to undo this piece of misinformation. If you were in soil, what I said here is correct, IMHO, but, in a soilless medium all of a sudden the runoff can tell you some things. In this type of medium, you can actually tell whether your nutes are being used and whether salt is building up so that you need to flush. This thread has been a reminder to me to get back to paying more attention to the medium and not automatically assume it to be soil.

 

[Bibo2222]

well, the compost and humic acid says to me that it is a soil, and not a soilless medium, but it is pH'ed as if it were to be used as a hydro system, so it is a little confusing. In your research have you found anyone else using this soil who has a pH recommendation? I would tend to think that with the ingredients listed in the order that they are, that this is a mostly coco/peat mixture, and should be run as such, as a hydro system in the 5.5-6.1 range.

With the base pH set to the high end of the hydro range, I bet you get a strong upward drift as the nutes are used up and the system reverts to the base pH of the medium and that of water. I bet you could come in low at 5.6 or 5.7 and then drift each time up to 6.1 or so... but it would also depend on how you want to run this stuff.
If you want to run it like you would a soil and let it dry out between waterings, come in with the pH low and let it drift upward. If you want to run more like a hydro operation (recommended) and water at least every day with aerated water, I would set the pH to 5.8 most of the time and once in a while give them a shot of 5.5 just to pick up the heavy stuff at the bottom of the range.

If i went your first recommendation and this is only for convenience sake, will it have any negative impact on the plant's health?
And for the second option (your recommend one), should i significantly reduce my water quantity in order not to over water?
And should i flush before i do all of this anyway regardless of which approach i would follow?

Sorry for the storm of question

 

[Bibo2222]

This whole last post was wrong, now looking more clearly at the medium and its needs, but I especially wanted to undo this piece of misinformation. If you were in soil, what I said here is correct, IMHO, but, in a soilless medium all of a sudden the runoff can tell you some things. In this type of medium, you can actually tell whether your nutes are being used and whether salt is building up so that you need to flush. This thread has been a reminder to me to get back to paying more attention to the medium and not automatically assume it to be soil.

It's a reminder for you and one massive goldmine of info for me, i owe you a big thanks!
I'll be reading more about how to read mt runoff from now on. But i would definitely love to hear your tips on this part

 

[Emilya Green]

If i went your first recommendation and this is only for convenience sake, will it have any negative impact on the plant's health?
And for the second option (your recommend one), should i significantly reduce my water quantity in order not to over water?
And should i flush before i do all of this anyway regardless of which approach i would follow?

Sorry for the storm of question

No, either method will work... there are 1000 ways to skin a cat.

if you went with the hydro method you would always keep the plant topped off... water would actually become your medium, the rest of the stuff there would just be plant holder and you would use more water. By using aerated water the oxygen comes in via a different route to the roots, so you can't overwater.

A flush is helpful to reset everything and clear any build ups, but since pH is the problem here I would simply adjust that one thing to see how that impacts things, before throwing every idea you have at this. Save the flush for a couple of weeks from now when the salts are starting to build up.

It's a reminder for you and one massive goldmine of info for me, i owe you a big thanks!
I'll be reading more about how to read mt runoff from now on. But i would definitely love to hear your tips on this part

I am primarily a soil grower who has only dabbled in the hydro side of things, so you would not be best served by me in this regard. There are plenty of people on here growing as you are doing though, and I am sure you will be able to follow along with someone and get some tips.

 

[Bibo2222]

Thanks alot Emilya for all your advices, now i have a base to start from in fixing this issue. I'll keep searching to learn more about this medium.
Again, thank you and wish you best of luck.