Open Structure

Open structure refers to cannabis plants exhibiting loose, airy branching patterns with significant spacing between nodes and lateral growth. Plants classified as open-structure typically develop fewer dense foliage clusters compared to compact phenotypes, allowing light penetration throughout the canopy. This trait is often associated with sativa-dominant genetics and certain landrace populations from equatorial and subtropical regions. Breeders frequently select for open-structure plants to reduce pest and pathogen pressure in humid growing environments, as improved airflow minimizes conditions favorable to mold and mildew. Environmental factors—including photoperiod, temperature, and nutrient availability—can influence the expression of this structural phenotype.

Breeders working in high-humidity climates or outdoors commonly incorporate open-structure genetics to improve disease resistance and canopy management. This trait is also valued in breeding programs targeting extended flowering windows and vertically-oriented growth patterns.