A drying room should sit at 60% RH and 60-65 F for the first week after chop, then drift a few points drier as the cure phase begins. Capacity scales with wet flower weight: 1 pint per day per pound of wet flower, plus a margin for the building envelope. A small commercial dry lands on a 150-225 PPD unit; larger rooms step up to 300+. Pick from Quest or Anden, sized to the room and paired with a controller that holds RH inside a 5-point window.
Why Drying-Room Humidity Differs From Grow-Room Climate
Grow and drying rooms are two different climate problems. In flower, the dehumidifier sizes against active transpiration at 75-82 F and 50-65% RH, steady load. A drying room flips that: plants are no longer transpiring, just passively releasing water as tissues dehydrate. The room runs cooler (60-65 F) to protect terpenes, RH targets are lower (55-62%), and the load is front-loaded, day 1 is heaviest and the curve falls off through day 7.
I dry at 60 F and 60% RH for the first three days, then walk RH down to 58% and 55% over the back half. Slow and steady protects terpenes and prevents the outer flower from sealing off while the core stays wet. For the VPD math and grow-room side, see the complete guide to dehumidifiers and climate management.
Target RH and Temp for Drying and Curing
The drying window is narrower than most growers realize. Above 65% RH at 65 F, mold pressure ramps fast. Below 50% RH, the outer surfaces seal before inner tissue finishes releasing water, leaving crunchy outsides and chlorophyll-heavy interiors. The reference numbers below are the targets I run, and they line up with what most commercial drying rooms hold.
The dry-to-cure handoff is where growers get into trouble. If RH falls too fast you cannot recover that moisture once flower is in the jar; too wet for too long and mold takes hold in a forgotten container. The cure-phase numbers in my humidity pack sizing guide pick up where this chart ends.
Sizing a Dehumidifier for a Drying Room
Two methods get you to a defensible PPD number. Use both, take the larger, add a 25-30% safety margin.
Wet flower method: 1 pint per day per pound of wet flower at chop. A 100-lb harvest needs ~100 PPD. Day 1 is heaviest (often 1.5x the average), so a unit sized to the average runs flat-out on day 1 and coasts through day 7.
Room volume method: cubic feet (L x W x ceiling) times a load factor of 0.05 PPD per cubic foot for a sealed insulated room, 0.08 for a leakier envelope. A 12 x 10 x 9 room is 1,080 cubic feet, or 54-86 PPD for envelope alone.
A 100-lb dry in that 1,080 cubic foot room: 100 + 54 = 154 PPD, plus 30% = 200 PPD recommended. The Quest Next-Gen 225 lands in that tier. Bigger harvests step up to 300+ PPD; personal dries (5-10 lb wet) drop to 100-155 PPD.
Quest and Anden Units Suited to Drying Rooms
Drying favors overhead commercial units with strong fans and tight RH control. Basement portables cannot move enough air evenly, and their humidistats run a 5-10 point deadband, too coarse for a good dry. Both Quest and Anden build their commercial lines for exactly this scenario.
One spec note specific to drying: PPD ratings are measured at 80 F (AHAM standard). At 60 F every unit loses capacity because the coil cannot pull as much moisture from cooler air, so derate by 20-30%. The Quest buying guide walks through the derating curve; the same logic applies to Anden.
Integrating With a Controller
A dehumidifier alone is half the system. The other half is an RH sensor and a controller that switches the unit against a setpoint. Built-in humidistats read at the unit's intake, not at flower level, so for a drying room you want a remote sensor at flower height in the middle of the room.
The setup I run: an environmental controller with a remote RH sensor at flower level, switching the dehumidifier's outlet. Setpoint at the day's target RH (60% on day 1, walked down across the week) with a 2-point deadband so the unit is not chattering. Alarms above 65% (mold) and below 50% (over-dry) push to my phone. The commercial dehumidifiers category links into compatible units, and the grow-room temp and humidity chart covers the wider window.
Frequently Asked Questions
Further Reading
- Complete Guide to Dehumidifiers and Climate Management: the pillar that covers grow-room RH alongside drying-room targets
- The Complete Guide to Quest Dehumidifiers: full model lineup, sizing tables, and Quest-specific specs
- Best Humidity Packs for Curing Cannabis: where the dry hands off to the cure
