DIY Hydroponic Garden Tower - The ULTIMATE hydroponic system growing over 100 plants in 10 sq feet - This DIY Hydroponic Garden Tower grows over 100 plants in less than 10 square feet, by taking advantage of vertical growth space.
Another version on rain gutter gardening. Want to grow a salad garden but have no room? Try gutters! Affix them to a fence, slope them for drainage, and voila! Of course,for this I'd need a backyard wider than a hallway.