Gardening is definitely possible while serving, at least in Eastern Europe. In Bulgaria (closed now) most of the people in villages supplement their food with gardens. I was not big into gardening before becoming a volunteer but I learned so much about it while I was serving. A lot of volunteers spent time helping people in their gardens, or caring for their animals in order to get to know people and build relationships. My house had a very large garden in the back yard. It might be a bit difficult depending on when you arrive to get a garden started the first year, but by the second summer you should be able to.
Of course, I assume this is different for different countries. But yeah, for me the locals were definitely gardening experts.