What causes nutrient lockout in cannabis plants?

Nutrient lockout occurs when your plants are physically unable to absorb essential nutrients, even though those nutrients are present in the soil or reservoir. The two most common causes are an incorrect pH level—which chemically blocks roots from taking in food—and heavy salt buildup caused by over-fertilization or poor-quality nutrients.

How can I tell if my plants have nutrient lockout?

Because the plant is effectively starving, a lockout closely mimics the symptoms of an actual nutrient deficiency. Early warning signs include yellowing leaves (chlorosis), severely stunted growth, brown spotting, wilting, and curling leaf tips. If your plants look hungry but you have been feeding them regularly, lockout is the likely culprit.

How do you fix nutrient lockout?

The most effective way to treat lockout is to flush the growing medium. Pour several gallons of pH-balanced water through your soil or hydroponic setup, allowing it to flow freely out of the bottom. This washes away the accumulated salts and resets the environment. Once the runoff water tests within the correct pH range, you can slowly begin reintroducing a light, diluted nutrient solution to avoid shocking the roots.