Deron Caplan
May 26, 2021
Three Tips for Controlled Drought Stress
Applying controlled drought stress in cannabis cultivation can enhance cannabinoid and terpene production—if done carefully.
Why it matters: Moderate drought, long used to boost essential oils in herbs like those grown in the Mediterranean, has been shown to increase cannabinoid content in cannabis. A University of Guelph study found that a single drought stress application increased THCA and CBDA by 12% and 13%, respectively. When calculated per unit of growing area, THC and CBD yields rose by up to 67%.
Tip 1: Monitor for wilting: In the study, drought was applied by letting container plants dry gradually under standard conditions. Wilting—defined as a 50% increase in leaf angle—occurred after 11 days and signaled rewatering. Since wilting varies by cultivar, visual monitoring or moisture sensors may be more reliable.
Tip 2: Time it right: Drought stress should be applied in mid-to-late flowering—ideally two to three weeks before harvest. Earlier application during vegetative growth reduces yield, while later application may be less effective in boosting metabolite concentration.
Tip 3: Don’t rush: Environmental conditions (e.g., high heat or airflow), pot size, and media type all affect how quickly plants dry out. Gradual stress allows acclimation—avoid sudden water withdrawal to reduce plant risk.
This method isn’t universally applicable, but it offers a promising tool for growers aiming to optimize quality.