First of all you will need to have wheelchair friendly surfaces for your parent, raised bed or not. Paths may be made of packed crushed gravel (the round stuff does not pack and a chair will bog down) or paved with stone or brick perhaps. It is possible to get around on a closely mowed lawn. but it takes up a good bit of energy that would better be used for that actual gardening tasks. There is a thread in this forum (back a bit) about slopes for wheelchair ramps ... check that out to be sure that no slopes are too steep.

It should be possible to get long handled tools (do a Google or Dogpile search on accessable/handicapped garden tools) or add extensions on to favorite tools if you are handy that way.

That would be a start and the act of trying out the familiar chores will lead to discovering just where the problems and obstacles lie. Each person has different needs and they are best addressed as they come up. Good luck and stop back here often.

Lee AKA Fireraven9
Great woods, you frighten me like cathedrals;
You howl like an organ; and our hearts of misery,
Rooms of eternal mourning where quiver ancient rattles,
Answer the echoes of your from the depths I've come to Thee.
- Charles Baudelaire, Obsession

The best place I know for a great choice of "Enabling Tools"
of all kinds, is a sponsor of GardenWeb, called Gardenscape Tools. Just call for their free catalogue. (they have a special one for Americans and it gives all the shipping charges.) Their catalogue is small, however, it is packed with many items in full colour, with exact descriptions of every tool and which tasks they will best serve. As I mentioned before they are a great place to do business with. They have a toll Free Number 1=888-472-3266. If this number does not work from the US their other number is 416-698-5339. They are in Toronto, Ontario, Canada.
I have compared their prices to some discount stores and they still manage to be a little less expensive. Actually, they are not expensive at all. If you are an American you will get a real bargain, because your dollar is worth so much more than the Canadian. You may order by phone (that is what I like best) because their well informed staff can answer all your questions immediately.
Also, their return policy if very good, should you receive something and it is not what you envisioned they will gladly refund your money.
May I suggest, even if you have little knowlege of gardening, it will help a great deal if you get excited, as that in and of itself will provide your parent with the encouragement they need at this time to restore their own self confidence in an activity they once enjoyed. Get the catalogue and go through it with them and perhaps if they can see for themselves all the items that can help them, it might go a long way to restore their lost confidence.
I know from experience how depressed and bitter a person can become, and how worthless you feel when you can only remember the time before you became disabled.
If I can be of further assistance, please feel free to e-mail me via GardenWeb and I will happy to my utmost to help.
Good Luck
Punky.

So Sorry, however, I just went back to re-read your post and noticed that you live in the U.K., therefore, the part I posted about the United States does not apply, however,
as a sponsor of GardenWeb I am certain that Gardenscape is aware that these forums reach the U.K. and perhaps if you called them they would send you a catalogue in any case.
Also, there was someone who posted a few days ago (rwh1 TS1 UK). They were offering all kinds of help. I would get in touch with them.
The other parts of my post still apply.
Sincerely,
Punky

I'm not sure what you meant about the comment about him not liking raised beds. I think you will need to set up some gardening alternatives ostensibly for "your" pleasure and then get him hooked. I recommend hydroponics.

Take a look at the link below and see what can be grown in a hydroponic system. All of this is in aluminum growing in 4' wide beds in a trays set 30" off the ground. The beds are only 3" deep so a wheelchair can slide under them if necessary. The height is adjustable, he might actually be more comfortable with beds at 24", no more than 24" wide to allow him full reach across the beds.

The beauty of hydroponics is that it virtually eliminates all of the physicall effort of digging, weeding and watering. You focus on seeding or starting transplants, trellising and pruning if necessary and harvesting and eating!

Here is a link that might be useful: My Florida greenhouse

To answer one question, in California the accepted incline for a ramp is 1 in 12, or one inch of rise for every foot of travel. Two in twelve is/was acceptable to me but three in twelve was a bit of a bear.
I built a small green house when I first had to use a chair for mobility. My son helped me and we had a blast. It wasn't anything special but I used packed crushed cinderblock to make the floor and the outside paths. It even worked for ramps with a wood retainer wall. Very inexpensive building material here in US. Instant drain, no puddles and as smooth on the chair as cement once we got it packed right. And it stayed in place, didn't track into the lawn or house and my son wears lug soled boots. Remember to, not all raised beds have to look like they are raised beds. Even tho I am recovered enough to work, I still like the way they look.
Looking forward to the end of winter already,
Wil

Here is a link that might be useful: Our garden and pond

Just checking to find out if you had any luck in contacting rwh1 1S1 in the U.K. and if he was successful in being of any help to you. He seemed very anxious to be of help when he wrote.
Also, the idea that Adriana G. has about Hydroponic Systems sounds very exciting to me. I am just sorry that when I required the same kind of help last year, the only advice that was available was a raised bed outdoors and it took a fair amount of planning and money to accomplish this task, as this was to be in the front of my house, and as Chef_Wil said I did care how it looked. Had I gone the Hydroponic route, I am certain that my gardening experiece would have been a whole lot easier. Punky.

You can disguise hydroponic beds behind very traditional looking planter boxes, so you can put them in the front of the house too.

hydroponics is one of my favorite hobbies, although i am not disabled, i think it might be easier for someone with limited mobility because you can adjust the height of the plants and there is no bending over to weed the dirt and other stuff like that. if you have any questions about hydroponics check out the forum here on GW or email me personaly and i would love to talk to you about it. thats just my $.02 ~Ryan

Wouldn't it be nice to build a demonstration accessible garden at local Botanical Gardens or at a rehabilitation center? It could be a combination of conventional and hydroponic techniques.

Things like Earthboxes would also be nice complements to this.

There is one in Chicago at the Chicago Botanic Garden! This does not help people not in that area, but the idea is starting to catch on at least.

Lee AKA Fireraven9
Crossing a bare common, in snow puddles, at twilight, under a clouded sky, without having in my thoughts any occurrence of special good fortune, I have enjoyed a perfect exhilaration. I am glad to the brink of fear. In the woods too, a man casts off his years, as the snake his slough, and at what period soever of life, is always a child. In the woods, is perpetual youth. Within these plantations of God, a decorum and sanctity reign, a perennial festival is dressed, and the guest sees not how he should tire of them in a thousand years. Nature RWE

Here is a link that might be useful: Chicago Botanic Garden - Horticultural Therapy Resources

Hi Mel,

Hope you've been able to find some resources for your parent. Here's a couple of sites in the UK that might be helpful.

http://www.hort.vt.edu/human/htuk.html
http://ourworld.compuserve.com:80/homepages/Jane_Stoneham/homepage.htm

Hope these help,
Newt