Where can bushes be planted?

Okay, so I did a few experiments in the past few days, and I will post what I found and what I didn't. For reference, when I say "adjacent tiles" I mean the three tiles above, the three tiles below and the two tiles on each side of the bush.

• You can plant bushes alone in the village. By that I mean that you can plant bushes anywhere in the main village if all its adjacent tiles are free.
• You cannot plant bushes on the beach. The two attempts at doing so have failed, so I conclude that it can't be done.
• You can plant bushes next to each other. I've attempted to plant a row of bushes, as well as three bushes in an L pattern, and both attempts succeeded. I don't know if you can plant a square of bushes (4 or 9 or + bushes), but I have no reason to think you cannot. I didn't do the test because I ran out of bushes, but if I can I'll test this and update this answer.
• You can plant bushes next to a tree. An attempt at planting a bush right next to a tree succeeded, so I conclude that it can be done.
• You cannot plant bushes adjacent to a river tile. I planted a bush next to a straight river going North-South, and it wouldn't grow.
• You cannot plant bushes adjacent to a cliff. Self-explanatory.
• You cannot plant bushes adjacent to a building or a public works project. In my opinion this is the most important test. I planted a bush at the following four locations: next to my house, next to Re-Tail's, directly above a lamppost and above-left the same lamppost (so left of the previous bush). All of these wilted. My conclusion is that you cannot plant bushes adjacent to a building or a public works project.
  Note: This last test cost me upwards 40'000 bells and 4 days to build/remove the lamppost and obtain the bushes. I strongly advise against attempting to reproduce this experiment due to the cost in time/money.
• Bushes can grow in a connection of 12 at most. This includes trees and stumps, vertically, horizontally, and diagonally. If a bush or a tree is planted near a sequence of twelve bushes/trees/stumps touching each other, that thirteenth sapling will not grow.

Other than these I haven't seen any limitations in where to plant bushes. Obviously since you need to dig a hole in order to plant a bush, you cannot plant a bush anywhere you cannot dig a hole (maybe I should've added that above, but oh well).

Hope this helps!