One other hazard is animals. A short fence of rabbit wire will keep cats, dogs, rabbits, etc. at bay. Deer have also been reported to be fond of hops. Rhizomes are available from an increasing number of sources. American Brewmaster in Raleigh, NC and Freshops in Philomath, OR are two well-known suppliers.
Cost is usually a few dollars each.
They should be kept in plastic bags, moist and cold in your refrigerator until they are planted. The AHA also has additional hops-oriented publications.