Cross-posted from Hippyshopper and updated.
Monopoly was an institution when I was a young lad and now I have a four month old son of my own I have to prepare for future playtimes. Imagine my delight when I read about Gardenopoly on Treehugger. You start off by planting various flowers in pots and slowly work your way up to your first greenhouse. There are pitfalls along the way though i.e. aphid infestations, a humungous water bill and so on. Plus you can learn about the outdoors whilst trying to become president of the Horticultural Society and avoiding the shame of having to weed for three turns. All the cards have facts about plant origins, appropriate climates, soil and care tips on the reverse. If that does not get him interested in the garden then I don't know what will. Available at Boardgames.com for only US$24.95