Beds raised 19", no wider than 48" with 48" wide roll through paths with a grade of no more more than 1" in 12" side-to-side or front-to-back, for rolling folks.

Beds raised 30" for walker users and very gentle slopes (1" in 12") The side wall will need to be a bit more rugged in this use as not only will it be a much taller raised bed, but walker (hemi or platform) users will tend to also use the structure to pull them selves along with. Again probably a no wider bed than 48" and 48" paths.

Before folks over look them, Braille and raised character signage, and afordable ways to make them is also probably something you want to have.

*If* the paths are VERY level sod may work. If not some solid surface is in order. Gravel, sand, bark chips, never ever, ever works. Never.

Tom, can you post more info on accessable beds and facilities for disabled gardeners? I manage the grounds of an extended care facility for the elderly and older disabled folks. The site is small but well planted in color and scented plants, raised beds and containers and an edible landscaping bias.

Seedman