Hi Tom, I suppose it depends upon the degree of sensory participation; planting, weeding, picking and cropping, smelling or just looking. It could also depend upon the varieties being grown; tall, medium or short. I think all countries have organisations that represent people with various disabilities and they should be right on top of this issue. I'm sure they'll at least have an opinion, that is if you haven't already approached them. If your having trouble contacting such an organisation, I'm sure your local hospital or local council could give you a lead. I would think that too low would be better than too high, as it would be easier to raise the surface level as opposed to lowering it, simply by putting boards around and building up. You could also try it yourself by borrowing a wheelchair and see what works for yourself and then consult with the groups further from a position of some insight.

I am arranging a community service project for the United Way. We are looking for plans/designs for building raised beds that are accessible to wheelchair bound gardeners. Is there any info you could suggest for me? Did you get info about that for your project?

Somewhere I saw a table garden designed for use by people in wheelchairs. Like a big, shallow box, maybe on sawhorses? Of course, it would be for growing shallow-rooted vegetables, like lettuce, etc. Maybe it was in Square-Foot Gardening by Mel Bartholomew?
We had raised beds when I was growing up, so my mother (who was in a wheelchair) could use them. I seem to remember that they were about 26" high, and maybe only 22" or so across. The idea about checking it yourself from a wheelchair is good. Even a chair would be okay for estimation, but remember that the wheels will put the person further away from the bed than just a regular chair would. Good luck!

Try the attached link for information on raised bed gardens for the disabled.

the link is:

http://www.hort.vt.edu/human/pub426020d.html

It's an article by Diane Relf that appears alot on the web

Her e-mail address is; pdrelf@vt.edu

Here is a link that might be useful: Gardening in Raised Beds and Containers for Older