After teaming with SF writer Fletcher Pratt in "City of the Living Dead" (May 1930), he wrote "The Voyage of the Asteroid" which appeared in Wonder Stories Quarterly (Summer 1932) and "The Man Who Awoke", a series of stories that was later published as a novel.
Manning gave up his successful writing career at the end of 1935 and devoted his time to a mail order nursery business he owned and managed. Apart from several short stories in the 1950s ("Good-Bye, Ilha!, "Mr. Mottle Goes Pouf" and "Men on Mars"), he never wrote any more science fiction. However, he was the author of a successful book on gardening, The How and Why of Better Gardening (1951).
His Novels
- City of the Living Dead co-authored with Fletcher Pratt (May, 1930 Science Wonder Stories), reprinted by Gernsbeck Publications in 1939
- The Voyage of the Asteroid (Summer, 1932 Wonder Stories Quarterly)
- Wreck of the Asteroid, Part One (Dec, 1932 Wonder Stories)
- Wreck of the Asteroid, Part Two (January, 1933 Wonder Stories)
- Wreck of the Asteroid, Part Three (February, 1934 Wonder Stories)
- The Man Who Awoke, Part 1 (March, 1933 Wonder Stories)
- The Man Who Awoke, Part 2 (April, 1933 Wonder Stories)
- The Man Who Awoke, Part 3 (May, 1933 Wonder Stories)
- The Man Who Awoke, Part 4 (June, 1933 Wonder Stories)
- The Man Who Awoke, Part 5 (August, 1933 Wonder Stories)
- The Call of the Mech Men (November, 1933 Wonder Stories)
- Caverns of Horror (March, 1934 Wonder Stories)
- Voice of Atlantis (July, 1934 Wonder Stories)
- The Living Galaxy (September, 1934 Wonder Stories)
- The Moth Message (December, 1934 Wonder Stories)
- The Prophetic Voice (April, 1935 Wonder Stories)
- Seeds From Space (June, 1935 Wonder Stories)
- World of the Mist, Part 1 (September, 1935 Wonder Stories)
- World of the Mist, Part 2 (October, 1935 Wonder Stories)