By Charlie  Patton According to the University of North Carolina’s Health Talk website, gardening has several “surprising health benefits.” Among them: It builds self-esteem; is good for the heart; reduces stress; makes you happy; boosts vitamin D; and leads to a healthier diet.  Some of Jacksonville’s most passionate amateur horticulturists wouldn’t be surprised to hear this news, and they share their thoughts about the many rewards of gardening. Preston and Joan Haskell     Joan and Preston Haskell’s gardens adorn their Ortega home along the St. Johns River. “To me, every...