Leaves turning yellow

[Stickers]

I am growing 3 plants, outside. One is doing fine, the others have leaves yellowing. One more so than the other. It started about 3 weeks ago at the bottom with just a few small leaves and has worked its way up past midpoint. Mostly shade leaves higher up.
I am growing in ocean forest soil and feeding 1 X week with fox farms nutrients + cal mag at 1/2 strength The plants have just started to flower. They are about 5 and a half feet tall in 15 gallon pots. I have not been watering to run off.
Looking at the pics in gwe's diagnostic pages it most closely resembles nitrogen deficiency. I tested soil with a cheap ph probe that only reaches about 4" down, and it read 6.5. Any thoughts? I'm thinking I should do a flush.?

[3Berries]

How hot is the root zone at peak heat? Any difference in pot orientation and direct sunlight?

[Stickers]

I forgot to mention that temps have been around 100 for that period. I put the 15 gallon pot into a 20 gallon pot and fill the void with soil for insulation, but I would guess it still gets pretty warm at the roots. I keep them in the same place but rotate them 45 degrees once a week

[GroBuddy]

5 1/2 foot in 15gallons bigger than most indoor grows plants will need more food as well.

Plz dont flush for a deficiency lol flushing is never needed

[GroBuddy]

The only thing to read rn if wanted to are soil ppms to see if theres food in the soil. If it's over 400 ppms you'll need a better ph check. Because if it's over 400ppms theres probably enough food meaning you've locked out and its probably a ph problem not allowing nutrient uptake. However being you're feeding 1ce a week at half strength would have me believe they are just hungry.

[Stickers]

Question: Should I raise the nutrients to full strength at 1X week or 1/2 strength 2X week?

[Stickers]

Ok, thank you, I will try full strength next feeding. I double pot to insulate the roots it gets hot here. But I get you, the soil I use is from last years grow. I have a mound of it.I'm too cheap to use fresh soil. I'm already sniveling to self about doubling up on nutes.
Your advice gave me another way of looking at this. I couldn't wrap my brain around a nute deficiency because I thought I was giving her everything she needed. It didn't occur to me that I wasn't giving her enough ( duh). Thanks again for teaching me a different perspective.

[GroBuddy]

Plant caddies and pot elevators work for me with heat. You're right pots with roots can not sit on hot surfaces. I live in alamogordo new mexico, it's a desert climate with summer temps of 120° not heat index but 120°F. I don't run photos outdoors but I'll do autos perpetually 24/7 365 minus a 2wk vacation most years. Nothing wrong with what you're doing with old soil if it works

[SoOrbudgal]

yes i'd feed that one more, it's funny how some same strain need more than it's sisters but looks like a big gal. My indica hybreds don't get that large an i top them so 6ft is about max. I use 15gal like yours and drill about 12 holes all around the sides. Keep it off the hot cement put it on a riser of some sort also. Good luck

[Stickers]

Thanks for your advice. Guess I need to give it a little more water and check runoff. I have an inner pot (15 gal.) that the plant is in and a 20 gal. outer pot filled with soil that the runoff would filter through. I'm wondering if the ppm would be somewhat off. I'll check it out. Thank you.

[GroBuddy]

Feed more at once not more times weekly.

[GroBuddy]

Why do you have pots like that? You're ruining that second pot of soil using liquids letting that runoff leak into it. Saucers and pot elevators