Iron Chlorosis

Iron chlorosis is a nutritional disorder in cannabis plants characterized by yellowing of newer leaves while leaf veins remain green, indicating insufficient iron availability to plant tissues. This condition typically emerges when soil pH is too high (alkaline conditions above 7.5), which locks iron into forms unavailable for plant uptake, despite adequate iron presence in the growing medium. Iron chlorosis can also occur in hydroponic systems with improper nutrient balance or inadequate chelated iron supplementation. The disorder is distinct from nitrogen deficiency, which causes older leaves to yellow first. While iron chlorosis does not permanently damage plants if corrected promptly, prolonged deficiency can impair photosynthesis and reduce overall vigor. Breeders and cultivators monitor for this condition as a cultivation marker rather than a genetic trait.

While iron chlorosis itself is not heritable, breeders may select for plant lines showing robust nutrient uptake efficiency or tolerance to variable soil conditions. Understanding iron chlorosis helps cultivators maintain optimal growing conditions, which is essential for expressing a strain's genetic potential.