In the whimsy-laden suburban world where Mrs. Montague and Mr. Capulet reside, the rivalry between these elderly neighbors is as deep-rooted as the lawns they tend. The contentious relationship spills over into their respective gardens, where, upon their departure, the charming realm of garden gnomes springs to life. The Montague garden is dominated by the , led by the dignified Lady Bluebury, whereas the Capulet garden is controlled by the , directed by the authoritative Lord Redbrick. Much like their human caretakers, these gnomes are embroiled in disdain for one another, setting the stage for a classic yet inventive tale of rivalry and romance, echoing the timeless narrative of "Romeo and Juliet."

The film unfolds with a quintessential showdown—a back alley lawnmower race. In this spirited contest, Lady Bluebury's son, , represents the zeal of the blues, while the defiant Tybalt symbolizes the reds' fervor. In a turn of events that cements the gnomes' enmity, Tybalt resorts to subterfuge to seize victory, leaving Gnomeo's lawnmower in ruin. This incident not only showcases Tybalt's underhanded methods but also ignites a desire for retribution within Gnomeo, compounded by the apparent insensitivity of Mrs. Montague, who swiftly commissions a replacement lawnmower—a "Kitty Clipper."

In the cloak of night, the narrative splashes into realms of intrigue as Gnomeo, accompanied by his comrade Benny, infiltrates the antagonistic red garden. Their mischief almost goes awry with Benny's inadvertent activation of a security light, compelling Gnomeo to flee. Yet, in this flight, he serendipitously encounters , Lord Redbrick's daughter, who is similarly camouflaged and on a solitary quest to acquire a unique orchid. This chance meeting, fraught with disguises and initial competition, soon burgeons into mutual attraction, setting in motion a tender yet precarious romance that both gnomes must clandestinely navigate.

As the secret rendezvous persist in a neutral garden, the presence of Featherstone, a wise, albeit pink, plastic flamingo, adds a layer of encouragement and sagacity to their budding affair. Meanwhile, traditionalism rears its head back in Juliet's garden, as Lord Redbrick attempts to pair her with Paris, a match met with little enthusiasm by Juliet. Her deft maneuvering to distract Paris by redirecting him to Nanette, her confidante, further highlights her resourcefulness in pursuing her heart's desires.

Amidst this backdrop of love and conflict, the story delves deeper into familial and societal obligations clashing with burgeoning personal freedom. Lady Bluebury is devastated when the reds strike, desecrating the precious plant nurtured by Gnomeo's late father. Driven by grief and duty, the blues urge Gnomeo to retaliate, thrusting upon him the moral quandary of avenging his father without compromising his love for Juliet. It is a pivotal moment of character development as Gnomeo hesitates, and ultimately refrains, from enacting vengeance when confronted by Juliet, deepening the bond between them and challenging the stark discord ingrained in their worlds.

Conflict escalates as Tybalt's aggressive pursuit of Benny places the friendship and integrity of the blues in jeopardy, culminating in a frenetic climax atop a runaway lawnmower. The spectacular showdown leaves Tybalt shattered against a wall, a casualty of his own recklessness rather than Gnomeo's doing. Yet, in the aftermath, the volatility of suspicion threatens Gnomeo anew, necessitating Juliet's audacious declaration of love, an appeal for understanding that begins to bridge the gnomes' age-old rift.

The narrative crescendos as the blues and reds prepare for all-out war, fueled by Benny's impulsive decision to unleash a formidable lawnmower—the Terrafirminator—upon the reds. This mechanical leviathan, however, only escalates the chaos, indiscriminately wreaking havoc upon both gardens and highlighting the futility of their animosity. Amidst this metaphorical storm, Gnomeo's resolve to save Juliet crystallizes, underscored by their mutual refusal to abandon one another even as the Terrafirminator looms ominously, propelling itself toward inevitable destruction.

In the engulfing tumult, a presumed tragedy strikes with the obliteration of the fountain—a symbol of Juliet's imprisonment by her father's fears. Believed lost to the devastation, Gnomeo and Juliet's apparent sacrifice precipitates a cathartic shift within their respective clans. The destruction fosters a newfound recognition of the destructive cycle of retribution, compelling Lady Bluebury and Lord Redbrick to embrace reconciliation over conflict, unwittingly paving the path for the lovers to emerge unscathed in a narrative twist both hopeful and celebratory.

In the triumphant denouement, where glue and goodwill mends not only Tybalt but also broken hearts, the film’s final tableau celebrates a harmonious future. United in matrimony atop a purple lawnmower—a vivid emblem of their merger—Gnomeo and Juliet's union becomes a testament to overcoming inherited biases and the transformative power of love. Featherstone's reunion with his long-lost partner further underscores the narrative's leitmotif of healing and new beginnings, leaving audiences with a resonant portrayal of peace, unity, and the joyous dance of a resolved existence in a once-divided garden.