Yellow leaves - please help

[thedeny420]

hi, i am not an experienced grower and cannot figure out if this is light stress or deficiencies that cause these yellow leaves...

first picture is the plant that appears to be most affected,

second picture is a plant that looks healthy to me

strain - royal wedding (emerald mountain legacy)
hybrid, allegedly 50% /50%
16 plants on 1,20m x1,20m
real flowering 3rd week / 5th week 12/12 lights
indoor, soil mix of about 40%perlite and 60%biobizz light mix in 11,5L pots

2x hortione 592 v2 led (190w each), so 380w in total the suggested range for the lights, according to the manufacturer is 50cm in veg and 35cm in flower. i never hanged them closer than 45cm to the top of the tallest plant (so maybe rather a deficiency?)

not air cooled, temperature between 22-29°celsius
rh is between 35-48% ph should be fine
used to have fungus gnats but they seem to be mostly eliminated
watering every 3-4 days fertilizer is BIOCANNA, always used a bit more than half of the suggested dosage (maybe too little?)

what i also have to note is that its only the upper leaves appearing more and more yellow, which would point to light stress, but as mentioned i put the lights even farther away than the manufacturers suggestions...


i would love if someone could 'shine some light' on my situation here.

 

[Emilya Green]

Your plants look hungry. Try the full recommended dosage of the nutes. More often than not, the manufacturers know a lot more about how to properly use their nutes than the typical online guru. You say the pH is fine... but lets check... what are you adjusting it to?

 

[thedeny420]

thanks for your quick reply. ph was always a bit above 6. i thought the same about upping the nutes to their full suggested level, but since it appears to only affect the upper leaves, doesnt that point to light overdose?

 

[Emilya Green]

thanks for your quick reply. ph was always a bit above 6. i thought the same about upping the nutes to their full suggested level, but since it appears to only affect the upper leaves, doesnt that point to light overdose?

no, the only thing that being in the upper leaves tells you is that the elements that are being needed are not mobile elements or the plant needs so much of it that it is showing up everywhere. Some elements can be stored in the big fan leaves and then moved around the plant as needed. Deficiencies that show up in the upper leaves are of elements that can not be moved and if they are not in the immediate nutrient mix, then the upper growth that needs that fuel is what shows the deficiency. An overdose will look completely different and usually causes the leaves to claw downward dramatically.

 

[Emilya Green]

thanks for your quick reply. ph was always a bit above 6. i thought the same about upping the nutes to their full suggested level, but since it appears to only affect the upper leaves, doesnt that point to light overdose?

The pH of what is above 6, the nutrient mix that you are feeding to your plants? How about when you do a plain water pass every other time? What pH are you adjusting that to?

 

[Fuzzy Duck]

Watering every 3-4 days fertilizer is BIOCANNA, always used a bit more than half of the suggested dosage (maybe too little?)

Looks hungry & as you mentioned perhaps a little to less ?

Interesting purple tinge to the outer margins of the serrated leaf


Most peeps will jump on the PH band wagon, lolz some may even suggest nutrient burn but you may appear to be under feeding for that to occur & No that being very hard to achieve with Biocanna (organic version).

Also light bleaching by led looks nothing like that with 2nd question if it was, why is not effecting the others ?


GENETICS

We are not all created equal !

Some times, some thing which can not be explained by normal means happens.

 

[thedeny420]

thank you guys for your quick answers. now i am convinced i have been under feeding. also talked to a local growshop guy, who had a similar opinion. so i will just use the full scheduled nutrients as described and see if that gets rid of the problem. since i am using organic nutrients, i think it might take a while for the plants to recover. i will post an update in a week or two.

thanks so much to both of you !!!!

 

[thedeny420]

The pH of what is above 6, the nutrient mix that you are feeding to your plants? How about when you do a plain water pass every other time? What pH are you adjusting that to?

i am lucky enough to live in a mountain town where we have almost perfect tap water conditions. i really think i got my ph levels in order. but thanks anyways for trying to eliminate every possible source

 

[Roy Growin]

The BioBizz combo nearly always needs supplemental CaMg and PK in flower
Just doesn't seem powerful enough and is an open invitation to fungus gnats
My tuppence, not necessarily worth that much

 

[thedeny420]

The BioBizz combo nearly always needs supplemental CaMg and PK in flower
Just doesn't seem powerful enough and is an open invitation to fungus gnats
My tuppence, not necessarily worth that much

thanks for the tip, what kind of soil mixture would you recommend? maybe good to know for future endeavours

 

[Emilya Green]

i am lucky enough to live in a mountain town where we have almost perfect tap water conditions. i really think i got my ph levels in order. but thanks anyways for trying to eliminate every possible source

ah grasshopper... you have given me a big clue. Congratulations on the great water by the way, I would love to live somewhere like that. Unfortunately, it is not the pH of your tap water that is important, it is the pH that your mix is at after adding nutes to the water. If your fluids are not set at 6.3 pH when they hit your soil or at least in the 6.2-6.8 pH range, your nutes are not working as they should be. That could be your entire problem.

 

[Roy Growin]

thanks for the tip, what kind of soil mixture would you recommend? maybe good to know for future endeavours

Erm... coco - I figure since I've gotta mix up stuff I might just as well use Coco/nutes, and I've never regretted it
Watering, nutes, pH, additives etc are a doddle in coco
Having said that, I would (as I used to) grow in LOS if I had the space as I believe the smoke is subtly superior

 

[Rolling Green]

Welcome thedeny420!

You got some great answers from very knowledgeable people here and hope to see some new pictures with bright green leaves in a few week and flowers fit for the cover of High Times.

I stick with outside and then only have to deal with the deer, wind, bugs and thieves haha. The deer eat all the bird seed and drink the bird bath water and think my garden is their kitchen.

 

[thedeny420]

update: watered them today with the full nute schedule. ph readings showed 6,4 on the mixture. lets see how this helps. thanks for all your helpfulness

 

[thedeny420]

i spoke to a grow mentor friend today (the only person i know personally who i really trust in this topic, he had amazing yield & quality results previously) and he said that i should not mess with the ph levels if i grow organic using soil. he said i really should not up or down the ph of my mixture since the organic soil will take care of everything. could i hear some opinions on this topic? i would be very thankful for different mindsets.

best

 

[SmokingWings]

i spoke to a grow mentor friend today (the only person i know personally who i really trust in this topic, he had amazing yield & quality results previously) and he said that i should not mess with the ph levels if i grow organic using soil. he said i really should not up or down the ph of my mixture since the organic soil will take care of everything. could i hear some opinions on this topic? i would be very thankful for different mindsets.

While generally true the thing is that it will happen best if the water being used, with or without added nutrients, falls within a preferred range. The recommendation in @Emilya's message (msg #11) is a range from 6.2 to 6.8 pH. When the liquid/water is too far out of that range the soil might not get enough of a chance to work the pH and make the benefits available.

If the water starts off at the high end the benefits of nutrients that are available at the low end do not come into play. Same thing happens if the water starts off at the high end since the soil will not benefit from anything that comes into play at the low end.

You can get an idea of what is available at what pH with many of the charts available on-line that show nutrient availability depending on pH. To find one of these charts do google style search using the keywords:
nutrient availability ph chart

 

[Emilya Green]

i spoke to a grow mentor friend today (the only person i know personally who i really trust in this topic, he had amazing yield & quality results previously) and he said that i should not mess with the ph levels if i grow organic using soil. he said i really should not up or down the ph of my mixture since the organic soil will take care of everything. could i hear some opinions on this topic? i would be very thankful for different mindsets.

best

All I can do is explain why pH is important. It will be up to you to decide who is telling you the truth. The soil actually has very little to do with things. Organic soil is simply dirt that has no man made crap mixed in with it. Your typical hardware store potting soil is usually organic. It has no magical properties and may or may not have buffers in it that set the soil to a base pH (dry pH) up near the upper end of the pH range recommended to run soil in. Using an organic soil does not remove the pH requirement when using synthetic nutrients.

What your friend was confusing while trying to relay it to you is that in truly organic grows, where you don't feed the plants bioavailable nutrients, but where you leave that job for the microbes to do, the microbes don't really care much what the pH surrounding them is. The plants and roots really don't care either. So your friend is right, in an organic grow you don't have to worry about the pH. The organic and usually mineralized soil your friend is likely using, it also doesn't care what the pH is and has very little to do with adjusting the pH of your incoming fluids.

The only time we should be concerned with pH is when we are not doing an organic grow, but we are instead feeding our plants with synthetic nutrients. Several of the components in most bottled nutrients are locked into a special bond so that they cant interact with the other minerals in the bottle. To get them to break out of that bond and become available to the plant, they have to be placed into a mix that is between 6.2-6.8 pH. Generally it is recommended to adjust your pH to the bottom of this range, so that immediately all of your nutes are available to the plant. As the plant uses up the acidic nutes, the pH will start to drift upwards towards the pH of the water itself and the base pH of the soil, and as long as the mix stays in this range, all of the nutes are available to the plant.

PH is very important, if you are using nutes that require the pH to be in a certain range. Hydroponic nutes have their range, and soil nutes have their own range that the pH needs to fall between. Your assuming that you don't have a need to adjust the pH of your incoming fluids simply has made a portion of your nutes unavailable for at least part of the watering cycle, and fully explains the problems you are having.

 

[thedeny420]

thank you for your replies. i have been measuring and adjusting the ph during the whole time, i just thought i did something wrong because of what he told me. thank you for your opinions. in the end it is always up to me to decide what to do. i just like having multiple opinions, the best case being professionally and logically explained ones (thanks for the helpfulness emilya ).
the discoloration of the leaves did not change for better or worse up until now, but they look overall healthier in my opinion. buds are getting frostier and denser every day also. will update new pictures soonish.
best

 

[thedeny420]

heres some pictures the last picture is the plant that was previously shown as the one that is most affected.

please, do let me know your thoughts !

 

[thedeny420]

also have to add, that according to schedule it should be ready in 3+ weeks.