Outdoor critical kush photo with starter preflowers

My one has shown some signs of copper deficiency and only the very edge tips of a few lefs have gone yellowish, possibly yours is extending further down the leaf? Have you fed any copper at all ? As usually cal mag doesn't provides it. I think it would benefit from some nitrogen too to restore some dark green colour on the plant .

High Frank, Most of the problems with cannabis deficiencies are due overfeeding. I would give the soil a flush and start over again after doing so with slightly less nutritions. I would flush only 1 time and let the soil dry out (almost) completely aftwerwards otherwise you create other problems. You can do this flushing by slowly pour water onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot. After the flushing when the soil is (almost) completely dry again you can continue watering like you are used to. And also start giving a small dose of nutes again. Happy Growing! 😋

Any deficiency doesn't start out looking like the worst case of it... in other words, everything is a PROGRESSION... Does it look like a calcium deficiency? Could be. Would be nice to have some information about what you've been feeding it, what the conditions are, what your pH is... you know, like things that are contained in a diary... but without that, all we can say is that this is the start of something... or not.... Good luck