just some notes. (i'll figure out yr wiki syntax and fix this. :p)
simulation of slow time scales
chaos. nature is chaotic. (chaos as a design tool)
simulation of the non-visual, of other senses. (of plant senses?)
All this time we've been thinking about RPG's because of the terminology of guilds and classes. BUT The Ultimate Expression of Brainless Gameplay is the “casual game” genre. and The King of all casual games is Match Three type puzzles. e.g. http://www.bigfishgames.com/download-games/genres/17/match-3.html
Use seasons as tools All seasons exist at the same time the plant can “dream” of a different season or shift between the seasons at will to take advantage of the benefits that season has to offer. (use in 'battle' between plants, an invading vine or weed for example.) uuh, need to think about how this would work more in-depth but suffice to say that one can see the same garden shifting through any time of year.
We can define a benefit to each season and the player could decide when to use that benefit. Depending on how well he or she prepared, the benefit will pay off more or less.
The interactive part should probably be 2D but we really should have a 3D representation. The design of the Nintendo DS comes to mind (lower screen for systematic input, upper screen for fancy rendering).
A plant always grows, mostly influenced by its environment. There's not much choice involved. Even when the player does not actively play, the plant will still continue to grow. So the impact of the player should be on making the plant more lush and more beautiful. Analogous with the way in which humans can tell whether a plant is “happy” or “healthy” by just looking at it (more and bigger leaves, more flowers, bright colours, etc).