Day 20 since light change and starting to see purple fan leaves???

[Smokeshow]

Ok, so today is almost the end of day 20 since the change to 12/12. I currently have 4 plants in my tent, 2 Deathstar and 2 Fortune Cookie x Dosi do (Humboldt freebies). I went upstairs to check on them after work today and the tallest plant (FC x Dosi do) is showing me something new - she has purple starting to show on the edges of some of the fan leaves.

I will try to answer all of the usual questions first.

Soil = FFHF
5 gal fabric pots
Nutrients = FF Trio (1/2 recommended dose + Calmag and using RO water. PH to around 6.5
Light = SpiderFarmer SE5000 currently at 50% output.
VPD is steady in the 1.1 to 1.2 range right now.

The other plants are doing fine, and the other pheno of this strain is not showing any purple. The leaves have always had a different "shade" to them, so I don't know if this purpling is just something plant is going to do, or if I am effing it up.

I don't think that it is light stress, but this is by far the tallest plant - the tallest top is 49" from the tent floor, so that puts that branch at 16.5" from the light. All of the other tops on that same plant are 20+ inches from the light. The other reason I don't think that it's light stress is that I think that it is praying pretty hard and actually wanting more light?

I don't want to make any adjustments and screw it up worse, so I figured that I'd ask the experts.

Thank you,
Smoke


Here are some shots of the plant with the purpling of the fans. This looks like praying leaves, right?

Here is a shot at some of the fan leaves showing purple edges.

Here is a shot of all four of the girls.

 

[Thukah]

My last few grows have overgrown my tent. I measure ppfd throughout the grow, I start to see leaves "praying" when my ladies get very close to the lights and im not willing to dim them further. Increasing the angle results in less light hitting that flat surface. The only purple leaves I have right now are the leaves getting blasted by the lights, and they are praying quite hard. The lower I look the more horizontal and greener the leaves are.
Whether or not you are experiencing this is hard to tell when its not a monocrop. I would start by measuring ppfd at the top of each canopy and go from there, some plants want more or less light.

 

[OldOneEye]

What have the temps been?

 

[Smokeshow]

Thanks fella's!

I will run up before lights out and try to get a measurement with the photone app and report back on the ppfd measurement.

I read that it could be a magnesium def causing it, but they are all getting 5ml of calmag with every feed & watering, so I didn't want to start jacking around with shit and get everything all out of whack.

@OldOneEye During lights on temps were maxing at 80 degrees during the first two weeks of light change. This week I have been keeping max temp around 76 during lights on. During lights off the temps go down to 69 or 70 degrees. Humidity is kept in check with the exhaust fans and keeping VPD in the 1.0 - 1.2 range so far. I expect the VPD to go up incrementally as I decrease humidity as we go through flower. At least that is how is goes in my head!

Thanks for the help!

 

[Smokeshow]

I just ran up and measured before the lights went out.

The top of the tallest top of the tent is getting 730 ppfd at 16.5" from the light.
The next tallest plant (right front) is getting 660 ppfd at 22.5". The biggest of the Deathstar (back right) is getting 530 ppfd at 26" and the smaller Deathstar is getting ALMOST 500 ppfd at almost 24 inches from the light.

But, that is with the photone app with a piece of paper over the camera as a diffuser.....so there's that. But as the Mythbusters used to say.... it seems plausible? LOL

 

[OldOneEye]

The only thing that comes to mind is a phosphorous deficiency

 

[yamyam222]

My last few grows have overgrown my tent. I measure ppfd throughout the grow, I start to see leaves "praying" when my ladies get very close to the lights and im not willing to dim them further. Increasing the angle results in less light hitting that flat surface. The only purple leaves I have right now are the leaves getting blasted by the lights, and they are praying quite hard. The lower I look the more horizontal and greener the leaves are.
Whether or not you are experiencing this is hard to tell when its not a monocrop. I would start by measuring ppfd at the top of each canopy and go from there, some plants want more or less light.

The praying you witnessed is more likely a sign of issues in your root zone. Over/under watering, out of balance PH, or nutrient lockout. Ironically lowering the light PPFD can exacerbate such issues by lowering your transpiration rates. Less fluid reaching the top. Negatively, affecting the health of the top of the plant making it more prone to light damage.

 

[yamyam222]

A few details that stand out:
1) Your pots are very large in comparison to your desired plant size. I doubt you have a very large and robust root ball. Meaning your plant could be over saturated with both water and nutrients.
2) Even with your issues. The other plants look healthy enough to get some good product. Chasing this now may just lead to more issues. Starting to look into better root management for future grows would be more beneficial-
A) Proper pot size.
B) Proper nutrient ratios.
C) Watering only the plant that needs water even though you have multiples.
D) Wait for real good dry backs in a large pot. You need a large plant with robust growth to get proper dry back on a 5 gallon.

Above all I would Never waste time on a bad plant when you have others that would benefit more from your attention. Yank that b*tch first before sacrificing anything on the good ones! Sometimes you get bad one. It happens.