Grow science
Know your numbers.
Every guide, calculator and free download, sorted by topic. Plain words, real math, no myths.
Climate & VPD
Temperature, humidity and the number that ties them together.
What is VPD?
The gap between how much water the air could hold and how much it does.
Read + calculator02Ideal humidity
There is no single right humidity. The table for your temperature and stage.
Read03Ideal temperature
Day, night and roots, and why temperature changes every other number.
Read04Leaf vs. air
Under LEDs your leaves run cooler. Your real VPD is lower than you think.
Read05Lower humidity
Too much water in the air? Seven fixes, from free to effective.
Read06Dew point & mold
The water in your air doesn’t leave at lights-off. When humidity turns into bud rot.
Read + calculator07Day vs. night VPD
Stomata close in the dark. Why the night needs its own numbers.
ReadLight
How bright, how much, and how to measure it.
Inside the plant
How leaves breathe, in the tent and on the windowsill.
Tools & free downloads
Measure right, print the charts, log every run.