Quick Tips and Suggestions from Honey of a Thousand Flowers
You can make a garland like this from almost any greenery. I use eucalyptus a lot, bay leaf or oak leaf are also nice. In the winter months all of the evergreen garlands that you see are made this same way.
If you are in a city with a flower market, you should be able to order bulk greens there (or even order a pre-made garland from a wholesaler). If you do not have a market but do have a business license, you can buy greens from a local floral wholesaler. You can also order in bulk from places like Costco or fiftyflowers.com without a wholesale license.