Every spring we get a wave of calls about caves that "suddenly" started growing the wrong mold, and every spring the actual cause is closer to a change in outdoor humidity meeting a room that only knows how to react on one axis. If your cave's climate control consists of a humidifier and a target percentage, spring is when that gap shows up.
Relative humidity targets vary by style — pressed cheeses like the ones most members are working with in this range generally want somewhere in the 85 to 90 percent band, while washed-rind and blue styles need it higher, closer to 92 to 97 percent, at slightly cooler temperatures. Members usually have that number memorized. What's less often calibrated is the airflow that's supposed to be doing half the work alongside it.
Why humidity alone isn't the whole system
High humidity paired with stagnant air is close to a recipe for the wrong kind of mold — it's the combination, not the humidity number by itself, that tips a cave from productive rind development into a problem you're scraping off wheels. Airflow's job is to keep moisture moving off the rind surface fast enough that it doesn't just sit there, without moving so much air that it dehydrates the rind instead. The range worth aiming for is gentle: think a light draft, not a fan pointed directly at the wheels.
Spring is the season this becomes visible because outdoor humidity swings faster than most small cave setups are built to track. A room that held steady all winter on a humidifier alone can start showing surface issues in March or April not because anything in the room changed, but because the air exchange with the outside world changed underneath it. If you've noticed a new mold pattern this month and nothing in your cheesemaking process has changed, the airflow side of the equation — not the humidity setting — is the first place to look.
Where to learn the whole system, not just the number
This is exactly the gap the federation's Humidity & Airflow Control course is built to close. It doesn't treat humidity and airflow as two separate settings to dial in independently; it walks through them as a paired system, including how to diagnose which half is actually misbehaving when a cave starts producing unexpected results. Members who've taken it tell us the biggest shift isn't a new number to hit, it's a better sense of what to check first when something looks off.
If your cave is entering its first real spring, or if this is the year you're finally troubleshooting a problem that's shown up every March for a while, the course runs through the Education Committee, and late spring cohorts are a good fit for anyone who wants a season of results to compare notes on before enrolling. Reach out to the committee if you're not sure whether your setup counts as a "system" yet or just a humidifier with good intentions — that's a normal starting point, and it's exactly what the course is for.
Timing matters here too. Trade coverage this spring has flagged the approach of the seasonal spring flush — the days-per-year stretch when milk supply peaks — as a period processors plan around carefully, and the same logic applies to your cave. A flush means more curd moving through your make room and, soon after, more wheels arriving in the cave at once. That's exactly the wrong week to discover your airflow has been undersized all along; a system that's merely adequate in a quiet month can get overwhelmed once flush volume hits it.
The International Cheese Federation (ICF) and More Cheese are entirely fictional. This post is demonstration content created for MemberJunction. All people, organizations, events, courses, certifications, figures, and quotations in it are invented, and nothing here represents a real association, a real business, a real person, or real professional advice.