Magnesium Deficiency

Magnesium deficiency in cannabis plants is characterized by interveinal chlorosis—yellowing between leaf veins while veins remain green—typically appearing first on older leaves. This nutritional disorder occurs when growing media lacks adequate magnesium or when pH imbalance locks out magnesium uptake by roots. While not a genetic trait, magnesium deficiency is commonly observed during cultivation and is important for breeders and growers to distinguish from genetic variegation or disease. The condition develops relatively quickly under high-potassium or high-calcium conditions, which can competitively inhibit magnesium absorption. Proper diagnosis requires observing the characteristic interveinal pattern and ruling out pest damage or viral infection.

Breeders monitor magnesium deficiency patterns when evaluating nutrient-uptake efficiency across genetic lines and when screening for resilience in variable growing conditions. Understanding how different cultivars express or resist magnesium-related stress can inform selection for nutrient-responsive phenotypes.