Lily flower for lesbians
1970s Japan
https://learnjapaneseanime.com/culture-custom/people/yuri-lilies-signify-lesbian-love/
Roses for gay men
1970s Japan (via Greek mythology)
https://en.wikipedia.org/wiki/Barazoku
Chrysanthemum for male homosexuality
Pre-modern Japan, contemporary China
The story Chrysanthemum Vow in the Ugetsu Monogatari (published in 1776) was not explicitly sexual but has been understood as having homoerotic overtones.
Shinji Takeda’s character in the “gay samurai film” Gohatto (1999) retells the story of the Chrysanthemum Vow while reflecting on the homosexual liaisons between his colleagues.
The association of gay male sex and the chrysanthemum still exists in modern China: https://xtramagazine.com/power/chinese-official-poster-accidentally-refers-to-gay-sex-in-prison-51020
“Cut sleeve” for male homosexuality
Pre-modern China, still in use
China’s gay emperor known for his 'cut sleeve' – The China Project
“Tofu Grinding” for female homosexuality
Pre-modern China, still in use.
Heung Heung: "We're Grinding Tofu", Didn't Know the Term Meant 'Lesbians' ~ Asian Entertainment Gossip
“Bitten Peach” for male homosexuality
Pre-modern China
The idiom of the half-eaten peach, or the more literally translated “leftover peach” comes from the story of Mi Zixia (aka Mizi Xia).
Homosexual Traditions in China - The World History of Male Love (gay-art-history.org)