Robertsanswered grow question 8 months ago Nitrogen toxicity is dark green. Shiney, leathery, clawing down leaves are all signs it can show. The shade of green in the plant tells you how much nitrogen is in the plant. The spotting on the darker green one might be from a strong feeding or was why you feed. Could be water left on leaves under light. Anyway they look alright. All but the 1 darker green plant would be a ideal shade of green to maintain.