Gardens are designed—by definition. Consider the Jansen butterfly peony garden at the Henry Ford Estate in Dearborn, Michigan where June is peony season. On the 10th I was riding my bike past it and stopped to admire it and snap some pics. Its visual features immediately tell us that that this is not just a natural flower patch. Wild flower patches usually have no recognizable features of planning or design. But this one certainly does.
This is a garden, designed and cultivated by an intelligent being—a human. It was designed deliberately, not by chance, to resemble the contours of a butterfly to be immediately recognized as such by other humans, not animals. That is to say, humans design most things for other humans, especially things with aesthetic qualities. When we do design and create something we usually have the full expectation that it will be intelligible to other intelligent beings that can recognize, appreciate, and understand them as such. Therefore, when we see something with obvious design (especially with aspects of beauty) we know with near certainty that it is the product of an intelligent mind with an artistic flare for the pleasure of human beholders that can recognize and appreciate the beauty and forethought of its design.