Potassium deficiency?

Hey guys,

Just need some input on what this may be and what to do to remediate this problem. Im thinking it's a potassium deficiency but would like a second opinion. Appreciate any help given!

Autoflower ZKITTLEZ

PROMIX MP
Dr. Earth dry amendments
DE premium gold All purpose fertilizer 444
DE HOME Grown Fert 463
DE Flower girl 394
Impello Tribus


Growing under Electric sky es300 LED at 50% 18/6

Yeah, looks like potassium.

The Dr earth nutrients don’t look like a complete plant food really. The ones I looked up don’t list any calcium or magnesium or other micros. They probably assume you are growing outdoor in soil where those are readily available.
Also doesn’t look like enough N at 4-4-4. But you probably need to pick yourself up some cal / mag additive. Or just switch to a more complete plant food like mega crop.

A large portion of your Promix is comprised of coco coir...this medium craves Mg. Coco also likes a pH of 5.8, vs a straight peat grow, and considering you have a mix of both, the correct pH may be somewhere between the two if you were growing in just one or the other. Considering what you're feeding and the size of the plant, I would say it's not a Potassium issue. It's most likely a pH issue and / or an Mg issue...which is evident by some of your other plants. If it were me, I wouldn't change anything other than getting a handle on your pH and foliar spray some Epsom salt. If you're short on Mg, you'll know it in just a few days when the plants green up from the foliar feed, meanwhile you're not goofing up the soil any more than it might possibly be. Just my two cents; good luck.