ACADEMY SERIES · EPISODE 19Pharmaceutical Cannabis

Humidity in Pharmaceutical Cannabis Drying

In pharmaceutical cannabis, quality is decided in two places: the closed rooms where the plant is grown, and the drying room after harvest. About three quarters of a freshly harvested flower is water, and it must be removed at a controlled rate without giving mould a chance. This episode covers humidity bands in the grow rooms, drying and curing conditions, the water activity target, the moisture load calculation and choosing the right dehumidification technology by dew point.

Published: 9 October 2026Narration: Turkish and English6:17

In this video

  • In pharmaceutical cannabis, relative humidity is 65–80% in the seedling room and falls to 55–70% in vegetative growth, 50–60% in early flowering and 40–50% in late flowering.
  • The quality target has two criteria: loss on drying of at most 12.0% under the European Pharmacopoeia, and a water activity of 0.55–0.65 for the dried flower.
  • Drying typically takes 7–14 days at 15–21 °C and 55–65% RH; the product is then cured in closed containers at 18–22 °C and 58–62% for 2–8 weeks.
  • Taking 100 kg of fresh flower from 75% to 11% moisture removes about 72 kg of water, an average of about 300 grams per hour over a 10-day cycle, but the unit is sized for the higher load of the first days.
  • Above a +10 °C dew point a condensing unit is efficient, while below +5 °C a silica gel rotor or hybrid system is needed; the drying room band lies at roughly +6 to +14 °C.

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