This is the first year I am also in a wheel chair I usually go outside to garden at daylight I cant find a solution either. good luck we will find a way.
Many parks have started putting in garden areas specifically for the enjoyment of those in wheel chairs. You may wish to check some of the park sites for ideas. Raised garden boxes would be a good idea as well. You could either have them the height to be worked from your wheel chair or if you are able to move out of your wheel chair and back by yourself, you may wish to have a sitting wall surrounding the gardens.
If you can get someone to help you build them, raised beds can be built to a height that will make them accessible for you. Directions here:
You could always purchase elevated beds if you can't find someone to build them for you, but they are pricey. Do you have a fence with a wide top-rail? If so, you could get some strawberry pots and plant all kinds of things in those. OR you could do Pallet Planters (the Pallets are FREE). Stacked to the height you wish from the Ground OR Vertical and then grow whatever you like! Wishing you the best of luck in your garden!
I had a friend who was in a wheelchair.. We put staggered raised beds on a coffee table (it looked like stairs.) But I remember her saying that if she could do it over, she would have bought one of those tables that wind up and down. It did work really well for her, though.
Sorry to come back to this, but I just found a video that might help you.. This is my favorite gardening show on Youtube "Growing Your Greens"