Nitrogen Toxicity
Problem: Dark green leaves, shiny leaves, clawing, weak stems, and overall slow growth. Marijuana leaves that are nitrogen toxic often get The Claw or talon-like leaves that are bent at the ends.
Phosphorus Deficiency
Issue: A marijuana phosphorus deficiency normally appears on leaves from the lower/older parts of the plant. The lower leaves might turn dark green or yellow, and begin getting areas or huge splotches
Copper Deficiency
Problem: A cannabis copper deficiency appears with leaf symptoms such as dark leaves that take on blue or even purple undertones. The tips and edges of leaves turn pale yellow or white