Sounds like a good idea.
Seriously though, that would be fun. It could be useful for growing certain plants that aren't native to the area, too.
Actually, I can see dwarves keeping plants, but they would be of the type they were familiar with. For example; glowing mushrooms make good room lights. Also, any plants symbolic of strength or wealth (whatever those might be).
I'm all for it. The more personalized each dwarf's belongings are, the better, in my opinion. A dwarf with "likes nature" in their personality profile should be expected to have some plants in their room.