let’s break down the cannabis flowering stage and how humidity, light, and environment play a role:

Cannabis Flowering Stage Overview

The flowering stage begins when you switch your light cycle to 12 hours light / 12 hours dark (or when outdoor daylight hours shorten naturally). During this stage, the plant stops focusing on leaves and stems and instead puts energy into bud development.

Stages of Flowering

Transition (Weeks 1–2)

Plants stretch quickly (can double in size).

First white pistils (hairs) appear at bud sites.

Humidity: 45–55% is safe here.

Early Flower (Weeks 3–4)

Budlets form, trichomes begin appearing.

Humidity should start dropping to 40–50%.

Airflow becomes critical to prevent mold.

Mid Flower (Weeks 5–6)

Buds fatten and get denser.

Nutrient demand increases (P & K).

Ideal humidity: 40–45%.

Any higher, and you risk powdery mildew or bud rot.

Late Flower / Ripening (Weeks 7–9+)

Trichomes mature (clear → cloudy → amber).

Pistils darken and curl in.

Humidity: 35–40% for best resin production.

Keep airflow strong — this is the most mold-prone stage.

Ideal Environmental Targets (Flowering)

Temperature (lights on): 68–77°F (20–25°C)

Temperature (lights off): 64–72°F (18–22°C)

Humidity: 35–50% depending on stage

VPD (Vapor Pressure Deficit): 1.2–1.6 kPa is ideal

What Happens if Humidity Is Too High?

High humidity will cause many troubles and growers will suffer losses. There will be Mold (Botrytis / bud rot) inside dense colas. The powdery mildew will show on leaves & buds. The high humidity reduces potency and aroma (less terpene preservation). If you are a commercial grower, please get in touch with us as soon as possible.