In my opinion, you can go one of two ways with this question. You can say that the orchard is the protagonist or you can say that the speaker (who is presumably the owner of the orchard) is the protagonist. I think it depends on your own point of view.
Clearly, the "person" whose welfare we are most concerned with in this poem is the orchard. We hope, along with the speaker, that the orchard will survive. To me, this makes the orchard the protagonist.
However, it is also clear that the speaker is the one doing most of the acting in this poem. Therefore, I think you can argue that he is the protagonist.