Peters, who was also a memoirist and performer of his own works, had heart problems and dementia, said his spouse, Paul Trachtenberg.
Compelled to write poetry after the death of a young son, Peters produced more than 30 collections, beginning in 1967 with "Songs for a Son." Over the next decades, his subjects ranged from the intensely personal to ruminations on historical figures such as Shakers leader Mother Ann Lee and novelist Nathaniel Hawthorne.
His reviews of contemporary poetry were collected in the irreverently titled "The Great American Poetry Bake-Off," published in four volumes between 1979 and 1991. The criticism brought him notoriety for disparaging the work of better-known contemporaries such as John Ashbery and James Dickey.
"Peters' criticism is not maternal," poet and critic Robert Blywrote in a 1981 commentary on the first "Poetry Bake-Off." He argued that Peters' book "deserves numerous readers, particularly among young poets dissatisfied with the celebrities who keep writing the same poem over and over again."
Among his students in the 1960s was future U.S. poet laureate Billy Collins, who called his UC Riverside graduate school professor a "critical influence."
"We would spend 30 minutes on 15 lines of Tennyson," Collins recalled years ago in the Coachella Review. "At first, I considered this a waste of time … but once I slowed down to his pace, I realized this was poetry from the inside, poetry as line, syllable, and ultimately, pleasure."
Robert Louis Peters was born in Eagle River, Wis., on Oct. 20, 1924. He was named after Robert Louis Stevenson, whose 1885 classic "A Child's Garden of Verses" was one of the few books Peters' family owned.
He earned a scholarship to the University of Wisconsin but was forced to postpone his education to spend three years in Europe for the Army during World War II. He returned to the university for a bachelor's degree in English in 1948, a master's in 1949 and a doctorate in 1952.
Peters began writing poems a few days later "as a way of keeping sane," he told The Times in 1997. "My son's image was painted on sand," he wrote in the opening line of the poem "Song for a Son."
He moved to California to teach at UC Riverside from 1963 until 1968, when he accepted a post at UC Irvine. He retired in 1992.
His son's death shook up other parts of his life, notably his two-decade marriage to the former Jean Louise Powell. "I decided I'd lived lots of lies in my life," Peters said in The Times of his divorce in 1973 and decision to come out as a gay man. His poems in "The Drowned Man to the Fish" (1978) reflect on the "harrowing" difficulties of leaving his wife and children.
He wrote often on gay themes, most provocatively in "Snapshots for a Serial Killer: A Fiction and a Play" (1992), inspired by the case of Randy Kraft, a self-hating gay man who was convicted in 1989 of killing at least 16 young men.
Peters' other works include the 1988 memoir "Crunching Gravel," an account of his life as a 12-year-old Wisconsin farm boy that the New York Times praised as "a fascinating, unsentimental look" at a piece of America's agrarian past.
In addition to Trachtenberg, he is survived by sons Rob and Jeff; daughter Meredith; and a grandchild.
Woo writes for the Los Angeles Times and can be reached at firstname.lastname@example.org.