I've yet to see an uninteresting Paul Schrader film, but this one didn't seem to come together. This was partly because, after First Reformed and The Card Counter especially, I can now easily spot his (well-documented) motifs. But that wouldn't account for the strange absence of a story behind what you can read in the synopsis. Indeed, as Brian Eggert writes in his review, "Master Gardener feels like little more than a variation on a theme, its performances and specific interest in horticulture result in appreciation for an otherwise minor effort for a major filmmaker."
Norma is unconvincing as written, often feeling awkwardly over-the-top in an otherwise restrained film. Narvel fares better. He has not only hidden his past but changed as a result of gardening, and his personal reinvention is believable thanks to Edgerton’s intense presence. [Furthermore,] when Maya learns of Narvel’s past, she overcomes her reservations rather quickly, leading to a richly symbolic but emotionally flat sex scene […]. It’s provocative imagery that Schrader hasn’t backed up with an understanding of Maya; the filmmaker is more interested in Narvel’s redemption, leaving Maya’s forgiveness underdeveloped.
— Brian Eggert (Deep Focus Review)
Schrader likens his creative process to a pair of wires: you put them together, and a current flows. But as long as the wires are touching completely, the viewer has nothing to do. So the goal is to pull them apart, little by little, while keeping the current alive. Despite Master Gardener’s many interesting ideas, Schrader pulls them too far apart, and his film loses its charge. Still, it’s encouraging to see how Schrader in his old age is trying to push past his own paradigms, to explore questions he can’t answer, and to write his way out of the morass of American violence. Master Gardener doesn’t get there; I hope we will.
— Robert Rubsam (The Baffler)