Years ago when visiting Gregg and Philip, I was taken to hoop houses covered in plastic to provide more heat for cuttings. That was before Sequoia propagated the more difficult things for them. Sebastopol is cold as far as rooting rose cuttings is concerned. Efficient propagation requires HEAT. Humidity is easier and cheaper to reproduce than heat. Sequoia's green houses regularly hit a hundred degrees and higher daily temperatures late spring through fall. Cuttings of most roses could be rooted in a week to two weeks, faster if mist was involved. That kind of heat dramatically improves not only speed, but ability to successfully root more difficult, slower growing roses. HOT day temps with warmer nights really pushes plant rooting. Your day temps are very nice for living and can make just putting a pot under another plant to root much easier than hotter weather can, but for production for a commercial need, it's just not as efficient..it takes longer and it isn't as successful for more harder to root or significantly slower growing types.
