This article is an attempt at deciphering the enigmatic title of Patrick Modiano's 2012 novel: why did he choose to call it L'Herbe des nuits, despite the book's apparent lack of engagement with plants? In Jardins de papier, Evelyne Bloch-Dano understands the references to nature in the rest of Modiano's œuvre as metaphors for the author's poetics of memory and childhood. I want to argue that another interpretation is possible if we fully consider the plant physiology of grass: unlike trees, it grows from the middle and in between other crops. My article builds on this singularity to flesh out the forms of "middleness" in Modiano's plots, writing style, and social "milieu." Such an attention to the specific process of plant germination provides a new entry point into his works and their numerous allusions to vegetation, such as the metaphor of Occupied Paris as a soil, a manure, or an "artificial flower." Like the narrator of Pour que tu ne te perdes pas dans le quartier, Modiano should be viewed as a "Buffon of trees and flowers," notably because of the various connections between flora and fauna throughout his texts. To sustain these hypotheses, the article engages with botanical and ecocritical writings on plants, meadows, grass, and class (Rachel Bouvet, Alain Corbin, Gilles Deleuze, Francis Hallé, Denise Le Dantec, Stephanie Posthumus).