Learn English – Origin of “the grass is always greener”

Results from a Google Books search strongly suggest that the expression originated (in print) in religious publications. At least in my search results, publications of the missionary wing of the Methodist Episcopal Church account for the first five matches, spread across a period of seven years. The earliest of these sources (from January 1910) credits the saying to a Commissioner McFarland, who may be the author of the third article cited below.

From "Never Paralleled in New York," in The [New York] Christian Advocate (January 20, 1910):

Many ministers have heartily indorsed the [Laymen's Missionary] Movement and will support it with their indispensable influence. With their cooperation failure is impossible, and it is the universal post-convention report from the other cities that all local causes have been helped on by the new impulse of the Movement whose watchword is "For the Other Man." As Commissioner McFarland said at the Astor dinner, The rising tide lifts every boat!

From "Japanese Church in Wonsan, Korea," in The [Nashville, Tennessee] Missionary Voice (May 1911):

Now the building of the church in Wonsan [Korea], of course, was not entirely, or maybe even mainly, responsible for the building of the great church at home. But at least it did not hinder, and who doubts that the enlargement of heart that came to them through that unselfish thing, the spiritual swing developed in that enterprise abroad, hastened and helped on the larger thing they would do at home? "The rising tide lifts all boats," and "the light that shines farthest shines brightest at home."

From Henry B. F. McFarland, "The Man by Man Rise of a Race of Men," in Association Men (January 1915):

The rising tide lifts all the boats upon it. All parts of the colored [Young Men's Christian] Association movement have shared in the new progress. Great corporations employing negro workmen—like the Newport News Ship Building Company, which has already started work, with its four thousand negro employees—see the advantage of such Associations.

From "Woman's Home Missionary Society," in Minutes of the One Hundred and Seventeenth Session of the New York Conference of the Methodist Episcopal Church held in First Church, Peekskill, N.Y. March 22, 1916 (1916):

Wherever there is an active, interested, wide-awake Woman's Missionary Organization there will be found a broadened vision, an increasing zeal along all lines, and a permeating spirit of the Christ-love that is most helpful. "The rising tide lifts all boats."

From Hugh Burleson, "The Progress of the Kingdom," in The Spirit of the Missions (May 1916):

The editor of THE SPIRIT OF THE MISSIONS is certain that he speaks not only for himself but for every official connected with any missionary enterprise when he declares that he would not, if he could, divert a single dollar from the relief of Europe. On the contrary, he rejoices when gifts for the war sufferers increase, not only because of his passionate desire that this awful suffering may be relieved, but also because he knows that "a rising tide lifts all the boats," and that every good cause should profit by the sympathy which this crying need awakens in the hearts of men and women who too long have been concerned chiefly about their own comfort and gratification.

From "A Hint from Harvard," in Harvard Alumni Bulletin (December 11, 1919):

There must be hundreds of Harvard men who on reading that [story] will directly double their subscriptions; the tale is so darned humane! I am not a Harvard man as you know, but the Top Sergeant and his wife make me double my paltry ten dollars. The psychology of the outsiders with colleges of their own to serve is quite correct. A rising tide lifts all the boats!

And finally, the cover of American Gas Monthly (March 1920) consists of the following quotation and subtitle:

"The Rising Tide Lifts All the Boats."

When the tide of public opinion swells through recognition of service well performed, all our boats will be lifted.

Basically what we have here is a slogan so successful that in a single decade it went from being a watchword—indeed almost a catchphrase—of a vigorous Christian missionary movement to becoming an inspirational proverb for members of the American Gas Association to contemplate.

The Phrase Finder explores three different possible origins in the following extract:

Grass up:

• In 2005, British newspapers picked up on a story about a burglar who had stolen cash, jewellery and an African Grey parrot from a house near Hungerford, Berkshire. David Carlile, widely described in the press as 'feather-brained', explained to the police that he knew that African Greys could talk and he didn't want the bird to 'grass him up'. Presumably, had the parrot been a Norwegian Blue, he would have left it to pine for the fiords.

First assumption:

• 'Grassing up' has been a commonly used expression in the UK since the mid 20th century, but is less common elsewhere. The first known use of 'grass' in that context is Arthur Gardner's Tinker's Kitchen, 1932, which defined a grass as "an informer".

• Grass was a well-enough established word in the 1980s to have spawned 'supergrass', that is, a republican sympathiser who later 'turned Queen's evidence' and informed on the IRA, and which gave the Brit-pop band Supergrass their name in the 1990s.

Second assumption:

• There is another route to the word and this is via rhyming slang. Farmer and Henley's 1893 Dictionary of Slang defines 'grasshopper' as 'copper', that is, policeman. The theory is that a 'grass' is someone who works for the police and so has become a surrogate 'copper'. The rhyming slang was certainly believed in 1950 by the lexicographer Paul Tempest, when he wrote Lag's lexicon: a comprehensive dictionary and encyclopaedia of the English prison to-day:

  • "Grasser. One who gives information. A 'squealer’ or ‘squeaker'. The origin derives from rhyming slang: grasshopper - copper; a 'grass' or 'grasser' tells the 'copper' or policeman."

• That comes only a few years after the term grass was coined and there seems little reason to doubt it as the derivation. The original users of the term 'grass up' were from the London underworld and would have certainly been better acquainted with rhyming slang than the works of Virgil.

Third assumption:

• Some have also theorised that the term 'shop', meaning 'give information that leads to an arrest', derives from the same source, that is, that, as 'grass' derives from 'grasshopper', then so does 'shopper'. The earliest known use of shop in that context dates from around the same time as the emergence of grasshopper. The issue of the magazine Tit-Bits for May, 1899 includes:

  • "[He] volunteered for a fiver to 'shop' his pals."

• As far as we know, African Greys don't go shopping.

The second and third hypotheses are supported also by the Word Detective:

• The use of “grass” as British slang for a police informer dates back to the 1930s, and is apparently a short form of the slang term “grasshopper,” meaning the same thing. “Grasshopper” itself is rhyming slang (“a secret language” in which words rhyme with a hidden meaning) for either “copper” (i.e., a police officer) or “shopper,” one who “shops” (sells) information to the police.