The image was not of someone gardening naked. It was a sexy picture of a very attractive young woman. Just imagine the same picture with the woman fully clothed and ask yourself if this picture would illustrate a general article about gardening. If I had to take a picture to illustrate naked gardening, I would have ask the model to bend her knees (because it is much more confortable) and I would have taken the picture from the opposite angle, with a focus one her hands which is actually the part of her body she uses to garden (or maybe there is a way to garden with one's vulva my grandparents never teached me of).

If you're still no convinced, just compare with http://en.wikipedia.org/wiki/Naked_hiking : people on the picture are hiking, not sexy posing while pretending to hike.