Excess Phosphorus?

Iam growing Dutch Treat Cbd.
Growing Medium Coco
Ph 6.3
Nutrient better Bloom (12:34:12) with Cal-Mag.
About 30 days into flower.

A week ago I observed nutrient burn (dark green leaves and burnt tips) so ramped the nutrients from 1300ppm to 400pm and flushed excess salts.

The concern I have is the yellowing. Is this normal?

Thoughts?

they look hungry dont see much burning honestly, did you cover potassium ? i see the rusting on the lower foliage could be ma or mg

yellowing of fan leaves is normal in late flower. You want to see this. If they stay green you likely have too much nitrogen and that makes for harsh sparkler bud. So you are looking good IMO.

Renfro said:

yellowing of fan leaves is normal in late flower. You want to see this. If they stay green you likely have too much nitrogen and that makes for harsh sparkler bud. So you are looking good IMO.

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This isnt late flowering and thats more for after the point you manage to grow green healthy to harvest which i believe would directly correlate with the fade'in of ferts and not a thread where there appears to be problems.

After the last thread where you said only using a scope on trichs could tell harvest i have to agree your simply copy/past'in generic bad info and that seems very counter to the high level that exists here.

Why do this?

Since it starts at the top of the plant, and the bottom looks normal, though very dark green, with a touch of nute burn. I would actually think from looking at it that you have a Sulfer issue. What I'm torn on is whether its a deficiancy or if the Sulfer isn't being absorbed for another reason. Your plants don't look underfed, which makes me lean towards a lock out issue perhaps.

Has the issue gotten worse faster since you flushed, or have you noticed the spread slowing at all? How wet is your medium staying, that can cause uptake issues as can PH issues.

Thundercat said:

Since it starts at the top of the plant, and the bottom looks normal, though very dark green, with a touch of nute burn. I would actually think from looking at it that you have a Sulfer issue. What I'm torn on is whether its a deficiancy or if the Sulfer isn't being absorbed for another reason. Your plants don't look underfed, which makes me lean towards a lock out issue perhaps.

Has the issue gotten worse faster since you flushed, or have you noticed the spread slowing at all? How wet is your medium staying, that can cause uptake issues as can PH issues.

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Flushing made the issue worse. My original assumption was over-fertilizing. This assumption appears wrong. So it could be underfeeding but also could be sulfur.
Looking online a foliar spray of epsom salts and giving a feed at the right pH seems like the best option.

There are multiple things I mentioned that will cause lockout other than just overfeeding, but 1300ppm is starting to really get pretty high. I can't find the chart showing which impacts which but overdoing certain main nutrients individually can also lock out specific micronutrients. At the moment I'm not sure which has the most impact on sulfer.

I am still torn though because flushing making it worse makes me lean towards an overwatering or PH issue that is causing the plants to not properly uptake the sulfer. Has the root zone been staying real wet by any chance?

Yes the root zone is pretty wet. Ok will add watering to the list and dial my blumat down.

Dear Lord, please allow another, my leafs are yellowing to learn to use the search feature...thank you

Herb & Suds said:

Dear Lord please allow , another, my leafs are yellowing to learn to use the search feature...thank you

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I laughed so hard I farted

Thundercat said:

There are multiple things I mentioned that will cause lockout other than just overfeeding, but 1300ppm is starting to really get pretty high.

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My runnoff is higher then that by double

If the roots are staying to wet the plants won't eat right. It's also possible you locked them out with the real high nutrients which is why they aren't drinking the water and staying to wet.....gotta love diagnosing plant problems.

Thundercat said:

If the roots are staying to wet the plants won't eat right. It's also possible you locked them out with the real high nutrients which is why they aren't drinking the water and staying to wet.....gotta love diagnosing plant problems.

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Been two days after turning the blumat down and the coco is drying out nicely.

Just FYI don't let it completely dry, it's a line you gotta find, despecialy with coco from my understanding.

Read the plants.

When they are firm and standing tall, they are loving the environment.
When they start to droop a bit is the indicator that they are running out of water and can't keep the cells hydrated enough to stay firm and do their job.

Probably lockout/PH imbalance

how much have you feed it and how often.
those NPK numbers are pretty high, and that won't take long to build up and imbalance nutrient levels.

Think of them as bank accounts, with funds in and out. As you water with nutrients, they are stored in the medium and used all at different rates.
starting with 12-34-12
say it uses up 10-8-12
now your soil has 2 - 26 - 0
add another full dose, 14 - 60 - 12
then uses up 8 - 10- 8
which brings us to 6- 50 - 4

See how the imbalance happens very quick. That's why balanced 10-10-10 or 20-20-20 are also not ideal. And if you use them, they should be used at 1/4 to 1/2 strength and built up. Also flushing every 3 or 4 watering is a good idea. or a high amount of run off with each watering to leach out and excess nutrients.

Also you might be lacking micro nutrients as well with the coco/nutrient combo.

What is your runoff EC?? and PH?

You might not flush everything out the first time.

I think the issue is both pH and buildup of nutrients. I lowered the pH of my water to about 6.1 as I noted that my pH of the water was about 6.5.
I did not think about checking the EC of the runoff and as soon as I started checking I could see this is a problem. The EC was initially 3000ppm and I kept flushing and flushing with half strength until I got the EC to about 700ppm.
I will see how the plant responds. I still have at least 3-4 weeks left based on previous efforts but could probably stretch to 5 weeks to get higher CBD and CBN content.

budchemist said:

I think the issue is both pH and buildup of nutrients.

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They can be the cause, and effect, of each other...especially in coco, happens rapidly....Keeping within the safety zone is walking a fine line, which is nice, because adjustments will actually take effect within the timeline of a flower cycle.
If you're the kind of fella who invests in quality tools, check out the Leap pH probe, by Bluelab…
Takes instant readings in ALL media, and liquids.... Game changer for my soil, and coco grows....