In a narrative sense, people are trees. There's a connection. They both come from dirt. They're both told to bear fruit. As the story continues, arboreal language is so often applied to humans that it's easy to miss, whether we're talking about family trees, passing along our seed, cutting someone off like a branch, planting ourselves in a new place, or bearing the fruit of the Spirit. It's hard to deny that trees mean something, theologically speaking.
This book is in many ways a memoir, but it's also an attempt to wake up the reader to the glory of God shining through his creation. One of his first commands to Adam and Eve was to "work and keep" the garden (Genesis 2:15). Award-winning author and songwriter Andrew Peterson, being as honest as possible, seeks to give glory to God by spreading out his roots and raising my branches in a way that no other tree can: "I trust that by telling my story, you'll encounter yours. Hopefully, like me, you'll see that the God of the Garden is and has always been present, working and keeping what he loves."
Sometimes he plants, sometimes he prunes, but in his goodness he intends to reap a harvest of righteousness.