It would appear that one has to apply a watermark that more or less ruins the photo (placed right in the middle of the interesting bits) in order to make it a truly effective deterrent to this kind of copyright violation.
I'm old enough to remember various past attempts in the digital world to make copyrighted material "radioactive" if used without permission, and they were all either incredibly disruptive or very easily bypassed. So in the end I don't think the desired solution is yet at hand, or ever will be. Not to be negative, just realistic, and curious to know if I might be wrong. In the meantime, the whack a mole game must go on.
I also do not identify with the watermark snipping mentality, the appropriation of somebody's work without even asking. It's not like we individual gardening enthusiasts are getting rich off our photography anyway, and it's not like we wouldn't be generous if asked.
At some level this situation feels a little like the public gardens that I have contributed to. You put a pretty plant out there that you have raised from seed or whatever, hoping to turn it into a public good. And then somebody notices it one day and takes it home. A small percentage of people will see something pretty in public and decide it should be theirs. I keep putting these things out there anyway (in physical and virtual form) because I have come to accept some appropriation as a cost of participation, to the extent that it can sometimes be managed.
