Scottish novelist and poet Robert Louis Stevenson visited Caliornia’s Napa Valley and spoke to its wine growers in 1880, resulting in the travel memoir The Silverado Squatters (1883). Stevenson’s much-quoted words ”...and the wine is bottled poetry…” appear on a Highway 29 sign welcoming visitors to Napa Valley.
 
A book published in 1887 (see below) stated that “champagne is bottled poetry,” but the champagne version never caught on. Clifton Fadiman (1904-1999) is often credited with saying “wine is poetry in a bottle,” but it’s not known when he said this or if he was referring to Stevenson’s words.
     
 
Wikipedia: The Silverado Squatters
The Silverado Squatters (1883) is Robert Louis Stevenson’s travel memoir of his two-month honeymoon trip with Fanny Vandegrift (and her son Lloyd Osbourne) to Napa Valley, California in the late spring and early summer of 1880.
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The Silverado Squatters provides some interesting views of California during the late 19th century. Stevenson uses the first telephone of his life. He meets a number of wine growers in Napa Valley, an enterprise he deemed “experimental”, with growers sometimes even mis-labeling the bottles as originating from Spain in order to sell their product to skeptical Americans. He visits the oldest wine grower in the valley, Jacob Schram, who had been experimenting for 18 years at his Schramsberg Winery, and had recently expanded the wine cellar in his backyard.
 
Napa Now
When did Robert Louis Stevenson say that Napa Valley wine was “bottled poetry”?
Actually, he didn’t. He said that “wine” was bottled poetry. And he was referring to French wine when he wrote in his book The Silverado Squatters “...and the wine is bottled poetry.”

But he wrote the book while he and his bride were staying on Mount St. Helena, so the Napa Valley claims him as one of its own. And he’d certainly say it about Napa Valley wine if he were around today. Wouldn’t he?

Poem Cellars
”...and the wine is bottled poetry”
—Robert Louis Stevenson, The Silverado Squatters, 1883

It is this famous quote seen on the landmark sign on Highway 29 that elevates Robert Stevenson to the status of patron saint of Napa Valley wine culture.
 
What does “bottled” poetry mean?
A poem engages and changes us.

Sterling Wine Online
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Google Books
The Silverado Squatters
By Robert Louis Stevenson
Boston, MA: Roberts Brothers
1884
Pg. 48 (“In the Valley”):
Wine in California is still in the experimental stage; and when you taste a vintage, grave economical questions are involved. The beginning of vine-planting is like the beginning of mining for
Pg. 49:
the precious metals: the wine-grower also “prospects.” One corner of land after another is tried with one kind of grape after another. This is a failure; that is better; a third best. So, bit by bit, they grope about for their Clos Vougeot and Lafite. Those lodes and pockets of earth, more precious than the precious ores, that yield inimitable fragrance and soft fire; those virtuous Bonanzas, where the soil has sublimated under sun and stars to something finer, and the wine is bottled poetry; these still lie undiscovered; chaparral conceals, thicket embowers them; the miner chips the rock and wanders farther, and the grizzly muses undisturbed.

Google Books
In the Name of the Tzar
By J. Belford Dayne
London: William Blackwood and Sons
1887
Pg.  31:
“Tom says that aestheticism and alcohol are synonymous terms, and that champagne is bottled poetry. He is such a goose, Tom is!”
   
Google Books
The Transforming Draught:
Jekyll and Hyde, Robert Louis Stevenson and the Victorian alcohol debate
By Thomas L. Reed, Jr.
Jefferson, NC: McFarland
2006
Pg. 203:
It is impossible to read the accounts of Lanyon in his cups or Jekyll with his cronies or, especially, Utterson basking in vinous warmth with the aptly named Mr. Guest without acknowledging that the author who claimed that “wine is poetry in a bottle” had as much Disraeli or Lord Salisbury in him as he had Gladstone. While the novella may checker the age’s faith in the restorative and vitalizing qualities of drink by associating them so strongly with the violent Hyde, its glimpses of the social and even rhetorical benefits of alcohol embody a Carnivalesque endorsement of Bacchus in the midst of a more apparently Lenten literary endeavor.
 
Cynthia Allen for Future Life Now
October 15, 2011
Wine is poetry in a bottle.—Clifton Fadiman