Califlower
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Suppose I'll jump in also with some thoughts / personal experience.
I believe the main reason that "classic cutting methods" recommend high RH is to reduce transpiration and thus moisture uptake during a time which a plant cannot uptake efficiently on its' own. As well, low light augments this by reducing photosynthesis, which will slow usage of stored nutrients within the plant. An interesting thing to consider with stored nutrients is mobile vs. immobile elements. One could theorize that immobile elements cannot be used in any great degree during this stage; as they cannot be relocated nor can new be absorbed without roots.
Now as to whether a cutting requires special high RH and low light; is more dependent on the method used for rooting. I've done most all methods over the years, I suppose and only certain cases would require a humidity controlled enclosure. If you are doing "old school" type cuttings where you put a cut into moist potting soil alone; then you will probably need to keep the environment around the plant high RH by an enclosure or dome. In situations like this; I've used sealable acrylic cases along with a moistened pea gravel floor in cases like this with 100% survival. However, this old school system is probably the most prone to issues and requires the longest time for rooting (2 weeks +/-). An easy way to tell if you have 100% humidity in any enclosure or dome is by having condensation apparent on walls / lid.
More modern types of cuts used in this industry are typically variations of some form of hydro (continual supply of moisture). In many of these scenarios, it is possible to not require any enclosure or lid and still maintain a "localized high RH area". The net result of any auto-watering method in root stage results in a higher moisture content in the medium (as opposed to a hand watered once cup). This moisture is continually evaporating into the air right around the cut foliage itself; thus augmenting RH in that zone. As well, certain auto-watering methods like DWC will further exacerbate this high RH area as a result of constant air exchange out of the water holding chamber. In cases like this, no dome or any enclosure can be utilized.
I guess a last note on light. Ultimately, light level is going to be related to how long your cuts take to root. The longer you typically wait for roots; the less light you should have. However, you can judge by watching your cut as it roots (more color loss by rooting point could use a bit less light). I don't imagine you need HID lighting during this stage, but outside of this; I've never had issues with various lighting methods. Typically I run around 1000 lumens per square foot for cuts.
Hope this helps.
I just wanted to say I've read this several times since I started trying to clone. It sinks in more after having tried cloning a bit. Some good tips in there, thanks. I do want to do the aero thing. Thanks for the tip on the 1000 lumens/sq. ft. I've seen the aerocloners with and without net pots, If not going into an aero setup, I guess the net pots aren't needed.