Light Green Color on Top of Canopy

I am growing in soil (10 gallon pots) and a couple of days from end of week 5 flower. A few of the small leaves on top are showing light green on the edges (first observed yesterday, spotted more today). Not sure what the plant is trying to tell me. Other than that, the plant has been mostly problem free. I did see some minor Calcium def on a couple of leaves. I began increasing cal-mag from 1/16 tsp to 1/8 tsp in the last 2 waterings. See images below. Help will be appreciated. Thank you.

Potassium deficiency

hotrodharley said:

Potassium deficiency

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I was thinking same, but usually see it on the bottom of the plant vs the top. I have some pure potassium (0-0-50) which should correct this deficiency overnight. Appreciate your input.

The3rdMan said:

I was thinking same, but usually see it on the bottom of the plant vs the top. I have some pure potassium (0-0-50) which should correct this deficiency overnight. Appreciate your input.

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Usually does start in the older leaves as it’s a mobile nutrient. But not always. Looks like just in a limited area too. I could be mistaken but the pattern says potassium deficiency to me.

Your plants are dark green and shiny, very fertilized looking. I doubt it a lack of nutrients in the soil. More likely it’s the start of lockout or a toxicity from too much.

93OG said:

Your plants are dark green and shiny, very fertilized looking. I doubt it a lack of nutrients in the soil. More likely it’s the start of lockout or a toxicity from too much.

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This is an organic grow and the strain is Kosher Kush. The leaves have been this color for several weeks. I haven't observed any signs this plant has been over fertilized. The dark green leaves are a characteristic of this strain.

I am using Dr Earth dry feed schedule. I think that Dr Earth's feed schedule is on the conservative side which is why you may see a deficiency, which usually turns out to be Calcium or Potassium related. The other two plants I'm growing (Blue Dream, Skywalker OG) have also been mostly problem free as I head into week 6.

hotrodharley said:

Usually does start in the older leaves as it’s a mobile nutrient. But not always. Looks like just in a limited area too. I could be mistaken but the pattern says potassium deficiency to me.

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Right, and it seems the remedy only requires a small amount of Potassium to resolve the issue. I'll check the plant at lights on to see if there is any more damage. I use a magic marker to mark the affected leaves so I can tell if the problem has been fixed.

fyi, the issue has not advanced beyond what was shown in the photos. So, HRR was correct in his diagnosis of the deficiency.

Just for the search bar people because I did this last week as well:

Light green edges = Cal-Mag or Potassium deficient