Infusing Rose and Spearmint Oils ..

I usually infuse my herbs in olive oil and let set for several weeks but I wanted to try this method using lard and the crockpot.Lard being what i had on hand and alot cheaper than olive oil. I will be using in my HP soap later on. So i harvested a batch of spearmint the neighbor had growing in her yard and some of my rose petals. I filled the crockpot with it all and then added 2 cups of lard . I plan to let this infuse on "warm" setting for several days . Alot of people infuse thier herbs only for 4 or 6 hours by crockpot but i want to be sure to get a strong infused oil. I want to try to root a few o fthe spearment plants in a pot for my herb garden later on. These may be too big to get to root . But i plan on trying :)