1 year late but here I am.
Rosemary is native here, we have incredible specimen around the coasts.
Indestructible while on the ground, it withstands crazy amounts of wind from the sea, months long droughts in sandy soil, over 40 degrees summers.
Seems to have no issues if started in a pot, pretty much every house have one for seasoning food.
Collecting one is a whole different thing tho, hard as hell, and even after a successfull collection they usually suffer and can die anytime.
Your best bet is airlayering the trunk or big branch with the tourniquet+ring cut method in May (mediterranean climate).
They airlayer very easily and in a matter of 1-2 months only, with lot of roots.
They behave like junipers, having different live veins with different part of roots that feed the respective foliage. So make sure to constrict all the veins when you airlayer.
If you want to collect them you need as many roots as possible, dont touch the foliage, dont bare root.
Misting the foliage should help.
I'm not aware yet if they need their own mychorrhiza like pines, it might probably be.
Like junipers but worse, don't prune them hard, root prune at minimum. You can pinch them.
Dont repot too often and dont put them in small pots. Very draining soil and let it dry before watering again. Full sun. Protect from frost.