Where did this saying come from, and what is its true meaning?
The phrase "Wake up and smell the roses!" appears to be a conflation of two separate phrases, namely, "Wake up and smell the coffee!" and "Stop and smell the roses". This is confirmed to an extent by the following ngram:
Going by the graph, the two "source" phrases appear to have become popular in the 1970s while the conflated version appears to have done so in the 1980s.
slang (orig. U.S.). to wake up and smell the coffee (also decaf, etc.): to be realistic or aware; to abandon a naive or foolish notion. Freq. in imper.
Popularized by the U.S. syndicated advice columnist ‘Ann Landers’ (1918-2002, b. Esther Pauline Friedman).
1943 Chicago Daily Tribune 18 Jan. 17/2 A few years back, when a wife told her husband to ‘wake up and smell the coffee’, it usually was said in utter derision. Now, when there is coffee to smell, she shouts it to him in supreme delight
1955 ‘A. LANDERS’ in Oshkosh (Wisconsin) Daily Northwestern 21 Dec. 23/2 Wake up and smell the coffee. Do you want a wife who smokes, drinks, likes taverns and slaps you around?
The phrase, "Wake up and smell the roses!", carries the same meaning, and going by the nGram and the results on Google Books, is used around the world albeit far less frequently than the other two.
I believe this comes from a mixing up of metaphors.
Stop and smell the roses (rough meaning: appreciate life).
Wake up and smell the coffee (rough meaning: get real).
The Half-Life 2 opening line "smell the ashes" is an obvious play on the idiom; also tying in with Apocalypse Now's line "I love the smell of napalm in the morning."
Also the idiom "to smell of roses" means that your character is unsullied.
There's this one instance that seems to mention the usage:
In NZ we use the phrase "wake up and smell the roses" to mean that someone needs to get realistic about a problem and stop avoiding the problem. ie. stop burying your head in the sand
-"lightmanz" Mar. 07,2007.
"Stop and Smell the Roses" was the title of a song by Mac Davis in 1974.
I could have sworn that I read this as a quote from "cowboy humorist" Will Rogers back in the 1920s or so, but I just spent more time googling this than it was worth and am unable to find any confirmation of this. (I did see that Mac Davis did a Will Rogers tribute: perhaps somewhere along the line I saw something with Mac Davis talking about Will Rogers and singing his own song and I conflated the two.)
The golfer Walter Hagen is quoted with numerous variations of this phrase,, "stop and smell the roses", "stop and smell the flowers", "take time to smell the roses", etc. That's the oldest source I could find.
Intuitively, the sentiment seems so obvious and the wording so straightforward that I expected it to be older, but ...