Also found in: Dictionary, Thesaurus, Medical, Encyclopedia.
To die after overexposure to water. Typically used in reference to plants and seeds. I'm worried that days of torrential rain will cause the flowers I just planted to damp off.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
[for seedlings] to die from too much water. All the new plants damped off, and we had to buy some from the nursery. The little seedlings damped off and withered away.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.