This past weekend I spent sometime talking with a gentleman I met on a service call last year. He lives in a community that in order to keep the resale value of the homes up forbade any garden except for flowers.
His answer was to build what he called stealth gardens. He raised the base of a wooden (Pressure treated wood) frame about 8" above the ground. The base was 4' X 8' and 8" deep. The 6 legs were reinforced by angle iron which he said "will last longer than I will at 58". The bottom had angle iron slats every foot and was covered by 1/4" fence material. The last layer of the box was 1/2" pebbles for 2", over that was crush and run for 2". Then he put in his moist soil up to the rim.
He made 4' sides made of the 1/4 fence grate and covered on the inside with window screen to keep insects out of his garden. Then the outer most was two sheets of Plexiglas with holes drilled for air which could be slide where the holes were blocked for the winter months.
The top was of solid Plexiglas over the wire mesh and screen. This layer could be raised to allow harvesting, watering and maintenance. He said every year he picked the bees off his porch and moved a nest into each of his 12 gardens.
To keep the nosy neighbors at arms reach he leaves a hornets nest in one tree and grows flowers in the area by the sides and radishes, tomatoes, beans, sprouts, herbs, and corn in the middle. He said he had used to use these for 20 years in New York City on his building's roof.
If the Dept of Agriculture begins stalking free growers as I suppose the E-Coli outbreak is designed to allow these will keep the peace fairly well.
The ones he showed me he had built catch basins in the trees under the limbs that funneled the water to the raised sides to allow water to enter when there was a drought injunction for watering as we should soon start getting from our Governors.