Green’s Dictionary of Slang

1. flattery.

1838		T. Haliburton Clockmaker II 95: Cant carries sway always now. A large party in the House, and a wappin’ large party out o’ the house, must be kept quiet, conciliated [...] and John Canter is made Lord Lavender.
1843		T. Haliburton Sam Slick in England II 160: You insensibly flattered my vanity, by assenting to my self-sufficiency, in supposing I was exempt from that universal frailty of human nature; you ‘threw the Lavender’ well.

2. something good, desirable.

1895		W. Pett Ridge Minor Dialogues 264: It ain’t all lavender.
1899		C. Rook Hooligan Nights 160: It ain’t all lavender goin’ on beat around the Walk.
1920		Ade Hand-made Fables 292: Life is not all Lavender to one who has to stay up every Night so as to postpone his Creep to a Cell overlooking Steam which escapes from a Laundry.
1995		(con. 1860s) P. Ackroyd Dan Leno and the Limehouse Golem 75: It’s not all lavender.

3. (US) effeminacy, homosexuality.

1954

S. Streeter This Is Buenos Aires 143: Don't mistake his snobbery and foppishness for lavender and a limp wrist. The pituco is a nuisance, but is not effeminate.