Readers of Web sites such as this one are often advised to contact cooperative extension services for the answers to questions. Why? Well, when it comes to growing plants, the soundest advice usually resides with experts who live closest to you. They know all about the challenges of your locale, because they've had to deal with those challenges themselves. But who are these experts and how do you find them? Marie Iannotti, About's Gardening Guide, provides the answers in this article on cooperative extension services.