Allot of people loved gardening when they were living independently at home.
A really great activity to do with everyone is to collect old crockery from op shops and goodwill stores.
We had a really good recycling shop at our local rubbish tip where people could drop of homewares, furniture etc and I would buy boxes of colourful old crockery, tea pots and interesting things to use as planters at a very reasonable price.
I would ask for succulent cuttings from staff, friends and I also had a big succulent garden at home.
All that is needed is some potting mix a large table area covered in newspaper or a large drop sheet. Old large spoons are great spades for everyone. I would usually set up the crockery/planters at each end of the table so everyone could view and choose their pieces. Buckets of potting mix at each end of the table and cuttings within easy reach for everyone.
I would make sure people in wheelchairs could sit at the table. Everyone would choose their crockery fill it with soil then place bits of cuttings in each container. Some residents would like to keep the occasional plant for their room but the majority was sold at our Annual Fete and was always a sell out and a great money maker.
I found this activity a very worthwhile one, very enjoyable and everyone could join in and use their green fingers. A resident would water and look after the plants until our Fete day arrived. They would be well established by then.