How do I know if my flowering cannabis plants need more light?

Your plants will display physical signs of struggling to photosynthesize. Look for leaves turning pale or light green, excessive vertical stretching (wide gaps between nodes), and drooping or curling leaves. Stretching specifically indicates the plant is actively reaching for a stronger light source.

When is the best time to increase light intensity?

You should increase intensity gradually during the early-to-mid flowering stages, but back off before harvest: Early Flowering: Slightly increase light (often by lowering the lights closer to the canopy) to support the initial shift into bud production. Mid-Flowering: Peak light intensity is required here to fuel dense bud formation. Late Flowering: You should actually reduce the light intensity slightly in the final weeks. This mimics the natural fading sunlight of autumn and prevents bleaching as the trichomes mature.

What happens if I increase the light intensity too quickly?

Sudden spikes in light intensity can severely stress your plants. This can lead to light burn (bleached buds), heat stress, stunted growth, or hermaphroditism—a stress response where the plant develops both male and female flowers, which can ruin your harvest by seeding the buds.

How many hours of light does cannabis need during the flowering stage?

To successfully trigger and maintain the flowering phase, photoperiod cannabis plants require a strict daily cycle of 12 hours of light and 12 hours of uninterrupted darkness. Boosting intensity should always happen within this 12-hour window.