The competition, run by the trust and London College of Garden Design, is open to graduates of the college. Perfetti used surreal imagery for the design, which focuses on the trust's Garden Collection range of products.
"I wanted to create something unexpected," he said. "Products become sculptural elements enhanced by decorative posts."
National Trust brand licensing manager Phillippa Green said: "By re-imagining products in the range, Zeno makes us look again at everyday garden tools."
The garden design will be unveiled at Hampton Court in July.