How to Control Humidity in Indoor Cultivation

Indoors, there is no wind or sun to dry things out. Water from irrigation, transpiration, and a closed cabinet raise relative humidity above 70%: then fungi, fungus gnats, and odors appear. Lowering it is not just 'putting a fan and praying.'

Measure Before Acting

A cheap hygrometer prevents blind decisions. Seedlings 65-75%; growth 50-70%; flowering or fruit set 40-55%. If it rises 15 points at night, the afternoon watering is excessive or there is no extraction.

Air and Absorption

An extraction duct with a carbon filter removes humidity and odor. Cross a smaller intake fan to avoid leaving the cabinet empty. In small cabinets, silica gel bags in corners and near shoes or substrate storage prevent condensation.

Do not confuse ambient humidity with wet substrate. You can have the air at 45% and the coco saturated: the roots will continue to rot. Drainage, perlite, and spaced watering fix that.

Odors and Neighbors

The carbon filter does not control humidity, but a properly sized extractor does move saturated air. Change it when it stops smelling like 'clean carbon' and starts to smell like plants.

What We Recommend at Control Garden

Silica gel in packs, aluminum ducts, and carbon filters to close the loop: extract, filter, and absorb excess.