Short Answer

A cannabis humidor with a hygrometer holds flower at 58% to 62% relative humidity. The hygrometer reads the humidity inside the container. Two-way humidity packs hold that number. Temperature stays at 60°F to 70°F. An airtight seal and darkness slow terpene loss and mold.

Cannabis Humidor Guide: Store Flower at 58-62% RH

What the Hygrometer Measures

Relative humidity (RH) is the amount of water vapor in air at a given temperature. RH changes when temperature changes. A jar at 62% RH at 65°F drops below that at 75°F. Read the hygrometer after the container sits closed for 2 to 4 hours.

Buy Cannabis Humidor Online: A Buyer's Guide for Fresh Flower

Analog hygrometers drift. Digital units read in 1% steps and cost $10 to $30. Salt calibration checks accuracy: a sealed bag with table salt and water holds 75% RH at 68°F. Adjust or replace a unit that reads off by more than 3 points.

cannabis storage cabinet humidor

Target Numbers for Cured Flower

ASTM D8197 lists 0.55 to 0.65 aw as the range for dry cannabis flower. Above 0.65 aw, mold and Aspergillus risk rises. Below 0.55 aw, flower crumbles and loses weight.

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Two-Way Humidity Packs

Boveda and Integra Boost packs use saturated salt solutions. They add or remove water vapor to hold a setpoint. Sizes: 2 g for 1/8 oz, 8 g for 1 oz, 60 g for 1 lb. Pack life runs 2 to 4 months in a sealed container. Packs stiffen or dry out when spent.

Container Types

Spanish cedar humidors fit cigars. Cedar adds aroma, so most cannabis users pick glass, stainless steel, or food-grade plastic with a gasket. A mason jar with a rubber seal works. Steel containers hold 1 oz to 1 lb. Wooden boxes leak vapor at the seams.

Setup Steps

  1. Clean the container with warm water. Dry it for 24 hours.
  2. Place the hygrometer inside. Do not open the lid for 4 hours.
  3. Record the reading. Compare it to the pack setpoint.
  4. Add the humidity pack sized to the flower weight.
  5. Seal the container. Store it in a dark drawer at 60°F to 70°F.
  6. Check the hygrometer every 3 days for the first 2 weeks.

Maintenance and Warning Signs

Open the lid for 5 minutes each week when RH reads above 65%. White fuzz, a sweet smell, or dark spots mean mold. Discard the flower. Recalibrate the hygrometer every 6 months. Replace packs when RH falls 5 points below the setpoint.