Hi michelle. Yes, you can use this sage for smudging, I do with the sage I plant. I love sage, the smell of it and the feel of it and all. It's a beautiful plant, and easy to dry too. I pick a bunch of it every year and hang it upside down, tied to a coat hanger, which then hangs in my office to dry. Just make sure it is not leaning up against anything, like a wall. It needs to have the air get all around it to dry properly.
You can also easily freeze sage to use in the dead of winter for your cooking, too. take an individual leaf or a stalk w/many leaves on it. wash it and dry it thoroughly and then lay it on a cookie sheet and place it unwrapped in the freezer for a few hours. Once it is completely frozen, then you can wrap it securely in plastic wrap and freeze it for future use. I also grind it up into small particles (for soups and such, and put it into ice cube trays, fill with water and freeze it that way. when you make soups or something where you need sage, you can easily add it to the pot.
one thing i need to say is that burning sage is a strong odor, and so I burn mine outside, as my husband does not like the smell of it burning. I would strongly recommend you do the same the first time. burn many leaves of the sage and then save the ashes for smudging in an airtight container. if you don't mind the odor of burning sage, then you can do it the 2nd time inside the house.