This information is straight from the Department of Neighborhoods website:
The Thomas Street Gardens received site control of the property at 1010 Thomas Street in the Capitol Hill area of Seattle in April, 1997. Lyle Grant, an architect, landscape architect and a Master Gardener drew up the plans for the Gardens which included thirty two plots and two ADA beds. To incorporate the concept of the hills of Seattle, he included a three foot high curved aggregate wall, adding the dimensions of height and depth and creating an illusion of the site being larger, since one does not see the entire Gardens at one time. This unique feature also gives the Gardens a feeling of being a neighborhood "pocket park" that just happens to have vegetables growing in it! The main path made of stone insures that the Gardens are accessible to all, and also hides the "dry wells" that are needed to provide drainage.
Other special features are the herbaceous borders and perennial beds in front of and throughout the Gardens and the rockery planted into the aggregate wall. The tool shed was built from a design by Param Bedi and adds a modern look to what is usually a plain utilitarian structure in many gardens. The front gate was also designed by Mr. Grant and the trellis ties in with the architectural details of the neighboring houses. A wrought iron bench designed and made by Lambda House youth working with artists from Pratt Institute provides a lovely spot under the wisteria from which to view the Gardens.