Cupping + spotting

[Jason Twice]

This look like a calcium or maybe phosphorus deficiency to me, based on the charts I've used. The problem is that I'm using full-strength cal-mag supplement (Fox Farm) and it seems to keep getting worse, albeit slowly.

Temps: ~75 degrees
Humidity: ~50%
Light: Hortilux Ascend 700w
Light Distance: 18-24 inches depending on canopy. Problem leafs are at 24 or more
PPFD: 500-1000 depending on canopy height

I have been watering every 3rd day, feeding once per week. Grow medium is soil. Soil and Nutes are Fox Farm.

Feeding at 1600 PPM (700 scale) with PH of 6.2-6.3

Runoff is reading about 5.3ph

I have no idea wtf the cupping is.

Thanks for reading, and thanks for any help.

 

[Crumpetlicker]

How much airflow have you got in that tent and how often do you exhaust the air?
That may be the cause of the cupping.
Do you let the pots dry out a bit between waterings?
What are you feeding them?
Maybe try replacing one plain water with an extra feed each week. Just do one plain water.

 

[crimsonecho]

is this a 4x4?

 

[Jason Twice]

How much airflow have you got in that tent and how often do you exhaust the air?
That may be the cause of the cupping.
Do you let the pots dry out a bit between waterings?
What are you feeding them?
Maybe try replacing one plain water with an extra feed each week. Just do one plain water.

I have a 6 inch can fan rated at 420 cfm on max and ducting running two rooms over.

I'm feeing them Fox Farm nutes with cal mag. I water every 3rd day and feed once a week. The pots are always moist but they do try pretty well I believe.

I just flushed the whole system with about 20 gallons of water and the runoff is still around 5.2-5.3ph at 500-600ppm.

OH, and yeah the tent is a 4x4.

 

[crimsonecho]

dim your lights to 60-70% then gradually turn up if needed looks like light stress to me

 

[I'm negan]

dim your lights to 60-70% then gradually turn up if needed looks like light stress to me

Light stress is a myth. You can have too much heat but not to much light. I know this isn't a popular opinion but the data backs it up. Under optimal conditions a cannabis plant can handle more light than you can possibly throw at it while maintaining temps. The real problem is people don't give them optimal conditions then blame the light intensity.

 

[SNEAKYp]

Light stress is a myth. You can have too much heat but not to much light. I know this isn't a popular opinion but the data backs it up. Under optimal conditions a cannabis plant can't handle more light than you can possibly throw at it while maintaining temps. The real problem is people don't give them optimal conditions then blame the light intensity.

Got a link to that data? I’ve put 4000 umols on plants and I’ve seen the diaodes burned into the leaves.

 

[I'm negan]

This look like a calcium or maybe phosphorus deficiency to me, based on the charts I've used. The problem is that I'm using full-strength cal-mag supplement (Fox Farm) and it seems to keep getting worse, albeit slowly.

Temps: ~75 degrees
Humidity: ~50%
Light: Hortilux Ascend 700w
Light Distance: 18-24 inches depending on canopy. Problem leafs are at 24 or more
PPFD: 500-1000 depending on canopy height

I have been watering every 3rd day, feeding once per week. Grow medium is soil. Soil and Nutes are Fox Farm.

Feeding at 1600 PPM (700 scale) with PH of 6.2-6.3

Runoff is reading about 5.3ph

I have no idea wtf the cupping is.

Thanks for reading, and thanks for any help.

I would expect calcium deficiency to show more in the new growth. Your new growth looks great.

This plant had something similar going on. I fixed it by adding a humidifier and putting my exhaust fan on a thermostat switch so it wasn't sucking the moisture out of the tent constantly. Perked right up in a few days. I'll confess i also added cal-mag but i really believe the humidifier was the key.

 

[I'm negan]

Got a link to that data? I’ve put 4000 umols on plants and I’ve seen the diaodes burned into the leaves.

 

[bam0813]

Light stress is a myth. You can have too much heat but not to much light. I know this isn't a popular opinion but the data backs it up. Under optimal conditions a cannabis plant can handle more light than you can possibly throw at it while maintaining temps. The real problem is people don't give them optimal conditions then blame the light intensity.

straight clown world. Better watch Bruce again

 

[bam0813]

Hi all, this is my first "serious" grow. Ive done some seed chucking and crude indoor growing but this is my first time really trying to do everything right

 

[I'm negan]

straight clown world. Better watch Bruce again

Yes, the professor of Plant Physiology at the University of Utah. Bruce Knows his shit.

 

[bam0813]

But I’m certain light stress is a myth

 

[bam0813]

You dont

 

[Autodoctor]

straight clown world. Better watch Bruce again

he must have fell a sleep during this class lol

 

[I'm negan]

Hi all, this is my first "serious" grow. Ive done some seed chucking and crude indoor growing but this is my first time really trying to do everything right

So I'm not allowed to have an opinion? I've been into cannabis culture for 20+ years. I've seen a lot worst starts to a grow. Please critique my 3 week old plants that started as seedlings under full blast LED light 18 inches away and thrived. How do they look honestly?

 

[crimsonecho]

Light stress is a myth. You can have too much heat but not to much light. I know this isn't a popular opinion but the data backs it up. Under optimal conditions a cannabis plant can handle more light than you can possibly throw at it while maintaining temps. The real problem is people don't give them optimal conditions then blame the light intensity.

not this

So I'm not allowed to have an opinion? I've been into cannabis culture for 20+ years. I've seen a lot worst starts to a grow. Please critique my 3 week old plants that started as seedlings under full blast LED light 18 inches away and thrived. How do they look honestly?

flip them and see

 

[SNEAKYp]

Bugbee has a certain rep and the video is detailed. However, I was looking for more peer reviewed work. Seems highly unlikely that a plant is able to absorb as many photons that you can throw at it.

 

[I'm negan]

not this



flip them and see

Really bro? Dudes PPFD is less than 1000 ! and you're gonna call light stress? That's less than sunlight by far?

and have you ever tried giving plants way more light than recommended and then giving them way more nutes than recommended to compensate and test this theory. Doubt it.

 

[I'm negan]

Bugbee has a certain rep and the video is detailed. However, I was looking for more peer reviewed work. Seems highly unlikely that a plant is able to absorb as many photons that you can throw at it.

It would be difficult to throw that many umols at anything without causing heat damage first. But maybe not impossible. The point is, it is very difficult to give a plant too much light and probably blamed way more often than it should be. That's such a common theme around here and every forum. It's either too much light or not enough cal-mag. Dude suggesting too much light when OP said he's got 500-1000 PPFD is a joke.