Definition - What does Stemmy mean?
Stemmy is an adjective used to describe a wine which may taste green or woody. This is a characteristic of wine which may have spent too much time macerating and/or fermenting with grape stems.
This may be a characteristic of Pinot Noir, Cabernet Sauvignon, and sometimes, Chardonnay, as all of these wines can be crushed and fermented with their stems.
WineFrog explains Stemmy
A stemmy wine characteristic can be a positive or negative trait depending on the consumer.
For some, a stemmy wine is undesirable as it can present green notes of grass and unripe green vegetation, which are often signs that the grapes were not able to reach full maturity. These characteristics can be harsh and sometimes overwhelming.
On a positive note, if the stemmy-ness is on the lighter side, it can add depth to the wine and round out the aromatics and body of the wine.