Fill a dry, heat proof jar or glass measuring cup about half full with rosehips. Pour the blend of oils over them, making sure the herbs are fully submerged and covered with at least an inch or so of oil.
Gently heat over very low heat (ideally 100°- 140° F) for 1 to 5 hours in a double boiler or crockpot. The oil has finished infusing when the color of the rosehips has been imparted. At this point, turn off the heat and let the oil cool.
Strain out the rosehips. They have little hairs that can be irritating to the skin, so be sure to use a fine cheesecloth.
Using a funnel, pour the oils into a glass bottle. Cap with a dropper top.