Borders of marijuana leaves are yellow

A question from a fellow grower:

Hi i was wondering why the outer borders of these leaves are yellow.
Otherwise the plants seem vigorous. They are under a 400w MH bulb with
reflective hood. I water just when the surface dries a bit and the soil
barely pulls away from the pot. I am using a weak solution of fert i
had for orchids it is 5-1-1

one thing I noticed. You said you water when just the surface gets dry and the soil pulls away from the container. Cannabis doesn’t like to have it’s roots constantly moist. I always let the plant start to droop a bit before watering.

Feel the weight of the container when watered and when completely dry. You should notice a difference. That light feeling is when it’s reallly dry. That’s when they need water. Not just when the surface is dry.

Another thing I see that I would wait for the rest of the folks to see and comment is the way the edges of the leaves are showing signs of distress. It’s possible that it’s nute burn. (even a weak solution might be too much if you add nutes every watering) It’s also possible that it’s too much salt if the water is softened. That would cause a potassium deficiency.

If these were my plants, I would withhold nutes for at least a couple of waterings and watch the new growth. (old growth won’t get fixed, it’ll stay the same.)

But again, there are more brains here than mine and you may find they’ve got better answers.


Agreed about over-watering maybe being part of the problem, the leaves do have a bit of the “bloated” look.

5-1-1 is also probably not helping, that is awfully high in the nitrogen compared to everything else, and this is by no means near a ideal NPK ratio for cannabis, not matter if it is in a veg nor in flower. Some of what is in the soil might buffer a little of what is too much and make up a little for this fertilizer’s short comings

And I know I sound like a broken record…but what is the pH? It could be some deficiency lockout due to pH.

Certainly the type of yellowing, the way it is bordering the leaves and the pattern, this does seem to point towards a possible potassium deficiency, this could also be pointing towards possibly sulfur or magnesium deficiency as well. Over watering alone can contribute to a calcium/magnesium deficiency.