In the traditional way of life gardens were a ceremonial event for all, an opportunity to give to the Earth as well as to receive. The seeds of good food are also the seeds of good relationship, so caretaking the garden is symbolic of caretaking all beings ... an offering to all.
If we just worry about the big picture, we are powerless. So my secret is to start right away doing whatever little work I can do. I try to give joy to one person in the morning, and remove the suffering of one person in the afternoon. If you and your friends do not despise the small work, a million people will remove a lot of suffering.