- an exceptional aptitude for gardening or for growing plants successfully: Houseplants provide much pleasure for the city dweller with a green thumb.
- US and Canadian considerable talent or ability to grow plantsAlso called (in Britain and certain other countries): green fingers
A knack for growing plants and keeping them healthy: “All my houseplants are in sorry shape; it’s clear I don’t have a green thumb.”
A knack for making plants grow well, as in Just look at Louise’s plants—she really has a green thumb. This term presumably alludes to the stained fingers of an avid gardener. [First half of 1900s]