SOIL HELP - Early flower, yellowing leaves

[ranxerox]

Hey All,
I have a White Widow Auto plant (Nirvana Seeds) in Fox Farm Ocean Forest soil (5 gallon fabric pot w/extra perlite). It is now at day 36 (day 15 of flower) under a Mars Hydro TS3000 LED (in an 8 x 4 tent with 9 other plants). I fed it for the first time last night using Fox Farm Big Bloom (3.75 mL/gal.) and Tiger Bloom (1.25 mL/gal.) which is 1/4 strength based on the Fox Farm soil schedule for late flower. It also got CalMag (5 mL/gal.). I decided to go with the late flower ratios as it is an auto (less is more, usually) and wanted to go light on the nitrogen.

Usually the Ocean Forest soil has enough in it to get the plant through the first 3-4 weeks but I noticed the plant looking a little pale a couple days ago so rather than wait any longer I gave it its first light feeding. However, this morning the yellowing seems to have gotten worse and I'm getting concerned. Here's what it looks like:

https://imgur.com/R1slEqA

https://imgur.com/gKmdm80

https://imgur.com/7hTQnN9

It looks to me like a nitrogen deficiency. Am I wrong? If not what do I do? Is it as simple as adding in some Grow Big (the high N veg component of the trio)? Anyway, if some more experienced eyes could take a look and give me their thoughts I would really appreciate it.

[OlderNOTwiser]

I'm no help, sorry, but I've gotta ask...did you run xerox?

[ranxerox]

You're right, you are no help . To answer your question; yes I did (actually I ran the xerox machine, I guess that's different tho)

[OlderNOTwiser]

So, yea...makin' some copies...at the copier...

[Gluteous]

Ya I would up the feeding. I've not ever fed less than half-strength FF nutes and if they don't respond, go full-strength. Different strains have different needs so it's not a one-size fits all.

[Gavin]

Not sure you should of be adding any food at this stage,
Fox Farm Ocean Forest soil is very hot soil from what I have read and your plant are small compared to the pot size.

If the tips of the leaves are burnt at the top of the plant nearest the led and the edges of the leaves are raised and the leaves are going pale, its light burn or heat stress.

[ranxerox]

Thanks for the feedback everyone. Gavin, I think you are correct re. nutrients. I used FFOF in my last auto-flower grow and only had to add 1/4 strength nutrients a couple times in late flower. I have been agonizing about this for the last few days and did some more investigating and now I think they might actually be experiencing nutrient lockout. My pH pen had drifted out of calibration and was reading a couple decimal points higher than it should have. I did a soil slurry pH test on the most affected plants and the numbers were not good. One sample read 4.9! I flushed one plant (which started at 5.5) but was not able to get the runoff above 5.9 despite running 3 times the pot volume of water (pH 8) through it. (which might be close enough for soil, I guess). I am not even sure if that was the right thing to do. Most discussions on the subject seem to be about prevention not remediation.

If someone has had this problem and knows what to do please, in the name of all that's holy, help me out. I'm about to throw these girls out a window (without letting go!).

[Rwise]

I would add pelleted dolomite lime to the soil as a PH up buffer, I would counter that with pelleted sulfur as a PH down buffer and let the plant take care of the soil.
Good luck!

[ranxerox]

Sorry for the delayed response. Thanks for the feedback. I decided to take my time and just water and feed lightly (keeping a close eye on the pH) and it seemed to help with most of the plants. However, my White Widow auto never seemed to really recover but limped along gradually losing more leaves while at the same time producing some ok looking colas, go figure. My question is; should I harvest this plant now (3 more days will be 9 weeks) or can I give it more time? The strain description estimates 11-12 weeks seed to harvest. I checked the trichomes and although there are a few cloudy and a few ambers dotted around (mostly on tips of sugar leaves) there are still a lot that look pretty clear. Here is a picture of the main cola:

https://imgur.com/a/Zq3o7XG

What do you guys think? Can I give her another week or do I need to chop now before things get any worse? This grow has definitely been a struggle! Thanks all.

[OlderNOTwiser]

Nice looking cola. What did you decide?