55 is borderline for me. Adding humidity will improve your early grow cycles. If you’re concerned about mold especially the powdery mold that would attack your cannabis plant simply add a fan or two. Mold needs stagnant air. Improving the air flow in your place will fix a lot of your mold issues.If you have a hydrometer you’ll notice with lights off that your RH actually goes up. Where I live In Illinois my rH without a humidifier is 60ish
Temps and humidity (I run my tent slightly higher in all aspects in the below)
Temps and humidity
Seedling Stage
(Germination) lights 18/6 or 20/4
- Seedlings and clones like high humidity levels of 65-75%
- Reason: The root system is not established
- High humidity levels allow water intake through leaves
- Temperatures with lights on: 68-77 degrees (lights off: 4-5 C° lower)
Vegetation Period - lights 18/6 or 20/4
- Humidity levels can be lowered by 5% each week (acceptable range: 40-70% - ideally 65-75%)
- Temperatures can be increased a little bit (no obligation - no higher than 86)
- Co2 during veg - add if needed
- Reason: Roots absorb more water; evaporation through leaves cools plant(s). If you’re soil is drying out quickly then your roots are drinking a lot to cool the top of the plant. If temps are high you may consider adjusting your light, add a fan, check exhaust, improve airflow intakes, ect.
- Temperatures with lights on: 71-82 (can be higher if using c02)
- Lights off: 4-5 C° lower - if you have a strong light or a light that puts off a lot of heat the reduction of heat happens on its own once the light is off - watch for extreme temp changes and adjust if needed)
Flowering Stage - lights 12/12
(important reduce rH for this stage)
- You can get away with 55% (anything over 60% is real bad)
- Push more co2 high for the 1st 4 weeks of stretch/flower
- It’s best to slightly lower temperatures in flowering
- Temperatures with lights on: 68-78.8 (avoid high temperatures if possible
Dialing In temps and humidity in a grow space is 90% of growers problems (made this stat up). It’s difficult to maintain perfect conditions so just try to get close. If you get close you’ll be fine. My current grow saw rH of 75-85% all the way from seed to flower where I started stepping it down 5% using a dehumidifier just prior to flip. It’s important to note that a dehumidifier will raise temps slightly depending on your unit