OGgrowsanswered grow question 5 years ago hi mate, the tips of the leaves are dry and curling upwards, I also notice some yellowing in the leaves between the veins of the leaves, these symptoms seem to me to be lacking in magnesium. as you say that from this fertilization overdose, the excess of potassium can affect the roots so that they cannot assimilate the magnesium present in the substrate. apply calmag or just magnesium to correct, epsom salt withs a good choice to correct the soil. good luck mate