Our 4h group has what they call the green team to help folks with gardening task.
I am also testing some ideas I have seen. I took pvc pipe (one rated safe for drinking water) will have to check the diameter but put them in the ground standing upright and put potting soil in each one and planted tomatoes in them. I saw this on a pbs gardening show, the gentleman was in a wheel chair and the tomatoes were at the perfect height. Course you will need help cutting and placing the pvc in the ground the first go around. I also built 2 raised vegetable beds using concrete block, 2 blocks high I can sit on the edge and garden. They are just wide enough I can reach the center on both sides. Husband was asking why we were building them, told him so when I get older I can still garden, he said building the concrete block bed was going to make us older....they are really heavy but don't cost alot.
Hope you can find help, and for everyone else it is always good to be ready for when we are older or have issues before hand. I know it is hard to believe but hopefully we will all get older.