Phin begins with a neatly trimmed hedge that someone stops caring for. Instead of dying, it grows wild, and the neglect turns out to be a kind of freedom. Flowers bloom everywhere, and butterflies arrive. The speaker seems to see this as something beautiful, not a failure.
Then the poem turns the hedge into a picture of human life. We grow, reach out, and bloom through our moods and moments, and the butterflies seem to stand for those who appreciate and look after what we offer. The tone is gentle and reflective, with a quiet acceptance in it.
The ending is darker. Growing too much means we no longer fit the world, and the poem imagines sharp cuts, scattered leaves, and vanishing butterflies. The final single word, "Overgrown," echoes the title and leaves a wistful, bittersweet mood: life is full and wild, but it ends.