Okay, let's brainstorm that. For a micro cache in an urban environment it might be possible to use the hide in a plain sight principle. What about a hidden compartment in a DIY birdhouse on a tree in a small park? I saw birdhouse projects online, but not sure I saw any actually on the trees around here, though.



FWIW, flower beds are maintained annually in a city, which might include some digging and even all the soil replacement. Tomato patches at the streets? Never saw any, but tomatoes growing involves a lot of watering, and a.f.a.i.r. soil replacement too, as tomatoes are sucking nutrients from it fast.

Back in Russia we were using rainwater pipes, coming from the roof of the building down to the ground level in our games, hanging stuff inside on a piece of wire hooked by the top rim of the last section of the pipe (No.4 on the image). Such pipes were on every house back then.