Garden environments that have well known happy associated scents can be a strong antidote to depression. Certain plants are great to touch with their variety of textures. Leaves feel differently such as waxy, smooth, or rubbery like the water lily. Also the bark on certain trees such as Cork Oak or Paper Birch are very interesting to touch. With this in mind plants made to touch need to be needle free and able to withstand being handled.
Taste is obviously one of the most common associations with growing plants.
Herbs and many foods that most of us enjoy come from plants. A beneficial part of raising plants that provide food is the feeling one gets from being self-sufficient.