Grow Guide . environmental control . G-06
humidity first,
temperature second.
Clone humidity and temperature are the two variables that drive every rooting outcome. Get them right and most cuts root in 7 to 10 days. Get them wrong and even healthy cuts from a perfect mother fail.
Cuttings have no roots. High ambient humidity around the leaf surface reduces transpiration to a rate the cutting can survive. Aim for 75 percent inside the dome for the first 72 hours.
Air temperature in the dome should sit between 72 and 78 degrees. Above 80, the cutting transpires too fast. Below 70, root development slows.
The temperature of the plug is the single biggest driver of rooting speed. A 17 x 19 inch heat mat under the tray makes the difference between rooting at day 7 and rooting at day 21.
Propagation tray on a heating mat. Humidity dome over the tray. Pre-soak rooting plugs in pH 5.5 water. Place cuts in plugs. Close the dome.
Once white roots appear at the bottom of the plug (day 7 to 10), start hardening off. Day 11: prop the dome open one inch overnight. Day 14: remove the dome entirely.
Put a hygrometer inside the dome and another outside it. The dome should read 20 to 30 percent higher than the room.
In a warm room with floor temps above 75 degrees, yes. In a cool basement, no.
Above 60 percent ambient is unusual. In that case, you can skip the dome and just mist lightly.
Too much humidity invites fungal contamination, especially powdery mildew and pythium.
Yes, but it is harder to control. A humidifier in a small grow tent works.
Put a thermometer with a probe in the medium, not just in the air.