Here is a good recipe for home made carpet refresher. Every store sells the premade powder you can sprinkle on your carpets that is laced with chemicals and artificial scents, here is a better and cheaper alternative. This recipe has only a few ingredients and is very easy to make and store. This is the recipe I have used.
2 parts Baking soda
1 part Borax
Aromatherapy oils (some choices are lemon, Lavender, any citrus scent) I recommend a good quality oil with out chemicals added to it.
All you do is halfway fill a small mason jar up with baking soda and put a few drops of oils of your choice in with the baking soda. Shake the jar and reopen to see if the scent is as strong as you want. You can add a few more drops in. What I did was let the mixture sit overnight to absorb the scents and dry before using it on the carpet. Then take the lid and poke about 6 or seven small hole on top. Close the top and you can just sprinkle the soda mixture on the carpet. After sprinkling on the carpet leave it on the carpet for about an hour before vacuuming