Maybe - but you've got me thinking. It may simply be climate - your France winters may be perfect for Rosemary cuttings and North America may have different wind/humidity/temperatures that simply aren't as plant-friendly.
Hugo Morvan wrote:It’s not the first time people from US tell me they have difficulty growing rosemary from cuttings. Maybe some odd difficult to clone variety is dominant over there?
Susan Boyce wrote:I have four large Rosemary plants and my cutting rate is about 50/50.
I take a cut, remove the lower needles, soak in water that I change out everyday until it grows white roots. I plant them in soil and wait and see if it lives then plant outside or give away to friends.