I do dome 80f and 80%RH
Important factors:
1. Do NOT give them to much light. (Most common mistake I see) this drives the plant to transpire and increases demand on nutrients.
18/6 they DONT need to rely on photosynthesis to make energy here. They are using stored energy and this is why a healthy cutting has a much better success rate.
Only enough light to prevent them from flowering. If you see them yellowing chances are to much light... and same for dropping to much light or a humidity issue. You can't over water a clone until it has root and is being driven to grow by light.
2000 lux is plenty.
2. Immediately dip or place into water after cutting. This will reduce the chances of an embolism... air in the stem. When ready to go into the plug dip in you rooting hormone and place into plug.
3. It ABSOLUTELY crucial that the plug is tigh to the stem.
I'm dam near 100% no matter the time I cut. With the exception of the forst time I used rapid rooters.... because the holes were to big so I flipped em and made my own as seen in the pics.
Nice healthy rooted clones... even from a plant in flower. Not haggard and turning yellow from to much light. Hell even ambient light is usually enough.