STILLWATER, Okla. – Things are looking up for gardening enthusiasts who want to think outside of the box – literally – and those with limited ground area for traditional gardens to grow fruits, vegetables and flowers. Growing plants vertically expands possibilities for garden spaces, said David Hillock, Oklahoma State University Extension consumer horticulturist. Although plants naturally reach vertically toward sunlight, vertical in this case refers to the surfaces they grow along. “Vertical gardening is a…