The main problem with both contemplating the future greenhouse and also playing with a bit of plant propagation is that after a short time, you start walking around eyeing plants and thinking about whether you want to take a cutting. Then you spend a lot of time thinking about how you would go about taking that cutting, which, if you are on state property, would not exactly be legal. Not, of course, that I would ever take a plant cutting on state property. But, you know, I walk around state property all day, and there are a large number of interesting plants there. And who would notice a six-inch twig missing from that fascinating maple? Nobody.
Even more insidious is the thought that you could gather seeds or spores from various plants. Seed propagation is much more iffy than cuttings, because you are relying on the plant breeding true, which it is unlikely to do. But you could get something even more weird and exciting, and thus the downward spiral begins, because seed propagators end up starting many times more seeds than the number of plants they eventually want. (This is how some of us have ended up with 30 grape vines on the side porch, not that anybody is naming names.)
Eventually, the house is just one large flat of seedlings, and outside are row upon row of small pots with baby plants in them. Roommates, neighbors, passing firemen are all recruited to help water the little darlings because the cause of all this chaos has waddled off 250 miles to the South for the winter, like some sort of low-motivation migratory bird.
This is the problem with plants.