Green gardening is all about being organic - avoiding the use of chemicals during the entire process. Whether you're living in the country or the city, a house or a small apartment, you can always find a place to plant something green.
Extremely Green is a great website that provides tons of information about gardening. This site is the best source for all of your organic gardening supplies and tips on gardening, the green way. Extremely Green offers solutions to lawn care, pest control, fertilizer and more.
Another thing to consider when thinking about green gardening is composting. Green Thumb Goodies will tell you, "[Compost] can be mixed into the soil before planting or applied to the surface of the soil as a mulch." If you have a place to put your trashcans, you probably have a little space to put a compost bin. If not,see if some of your neighbors are interested in composting too - if space is a concern, sharing a compost bin could be a great solution!
Location is obviously the main concern, but all you really need is a small space like a patio or balcony where you can set some pots and planters. Here are some great tips from Backwoods Home Magazine. If you're living in close quarters, but you still want to get a green garden going, start by learning how to garden in a small space and then refer back to the resources that will tell you how to do it organically!
Check out these links for more interesting tid bits about gardening and farming:
Career for the Year: Life on the Farm
How to get the most out of rain
Sustainable White Green House