grief, white hydrangeas
In part, The Haiku Society of America’s definition of a haiku reads, “Usually a haiku in English is written in three unrhymed lines of seventeen or fewer syllables.” Further, Japanese scholar Shigehisa Kuriyama states, “The 5-7-5 pattern by itself does not make a haiku.” (Gurga, p. 1). Contemporary English language haiku have departed radically from the 5-7-5 convention, including the Beat haiku of Jack Kerouac, Allen Ginsberg, and Gary Snyder, the latter awarded the Masaoka Shiki International Haiku Grand Prize in 2004. The haiku of Robert Spiess are especially experimental.
I recommend two sources for further study of haiku: “Haiku: A Poet’s Guide,” by Lee Gurga, addresses haiku in it’s traditional form; “Haiku Poetics in Twentieth-Century Avant-Garde Poetry,” by Jeffery Johnson discusses haiku as realized by modernist poets.
Speaking personally, it is most important for me to enjoy writing a haiku, correct form or not, and for my haiku to be enjoyed by the reader.