Depends on the genus & what uou entend to do with them may take anytime from late summer through late winter

From what I have read, humidity is really for the leafy part of the cutting, not important for root formation. So really, having an "enclosed" propagation box for hadwood cuttings is a bad idea unless you are someone who forgets to water. Is this correct? Having the roof on would be good for the leaves once they sprout on the dormant hardwood cutting, but then you have to go through the process of weaning them off the humidity - plus more humidity means more risk of mold and rot. This is from things I have read, I have no meaningful experience (I have rooted things but am not sure why it worked beyond the fact that the cuttings rooted before they rotted... in some instances - I certainly have rotted lots of cuttings in the past two). So use the roof "enclosed" humid system for softwood cuttings only? For hardwood cuttings really you just need the potting medium to be sterile, moist but not wet, and bottom heat. Air circulation and light will help prevent mold but watch out for cutting desiccation (sealing wounded areas of cutting that will be above soil line with wax could help retain moisture, or temporarily add humidity dome, mist etc. if that looks like things are a little dry). I read that a 1% Hydrogen Peroxide / water mix used for watering cuttings and misting works to prevent mold and even treat mild mold on cuttings in a propagation flat. I tried this for the first time today. Am I correct in this? Please comment, thank you! It's a blizzard here in Boston. Good day to garden indoors!

CPTK, how are your cuttings doing now? In my experience with roses it seems that just because the cuttings are putting out leaves that they are actually rooting. Sometime they are, and sometimes not. Hope yours have rooted by now. Let us know.

So it looks like both the batch outside and the batch inside are doing well. Both have pretty vigorous top growth now, so I believe they have roots. The batch inside is in coarse sand, so at the end of this week I will actually take them out of the sand and put them in individual pots. I'll know then for sure if they have roots. So the results of my hardwood cutting "experiment" are: (Note, batch 1 came from a different crape myrtle than batch 2 and 3. This is just one example of how this is not a controlled experiment. But it is instructive and confirms the common knowledge as well.) Batch 1. Dormant hardwood cuttings of crape myrtle were harvested and then immediately treated with rooting hormone and put in peat and perlite indoors under light. All these cuttings seem to have eventually failed. About half put out leaves, but stopped growing there, and then died. Batch 2. Dormant hardwood cuttings of crape myrtle were harvested, then soaked in cold water for 48 hours. They were then wounded, treated with rooting hormone, and planted in a garden bed outside while it was still winter. Half were stuck with about 1/2 of the cutting in the ground. The other half were stuck with only 1 node above ground. Several weeks later they came out of dormancy and are now growing vigorously. 100% have put out shoots above ground. The ones that are buried all the way except for one node are growing faster. Batch 3. Dormant hardwood cuttings of crape myrtle were harvested, then soaked in cold water for 48 hours. They were then kept in the frig in moist spagnum moss for about 3 weeks. Thereafter they were stuck in coarse sand after a rooting hormone treatment. These were not wounded at the time of sticking due to some evidence of root nodule formation which I did not want to damage. They were kept in a cold, dark garage with bottom heat until they unexpectedly started to bud out. At that time they were brought inside and put under lights. Although the cuttings that have budded out are now growing vigorously, about half of them have not come out of dormancy at all.