Are ageworthy wines always fermented with their stems?

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Dear Dr. Vinny,
As a newbie I have noticed that some of the so-called ageworthy wines that I have tasted have an herbal/green taste to them. Someone mentioned that it is due to the stems being present in the crush and that is needed for aging purposes. Can you enlighten me on this?
—Ed C., California
Dear Ed,
Sometimes stems are part of the fermentation process, and this can add a green note, but I would never say they are “needed” for aging potential.
Let me back up. First off, a green note in a wine is not necessarily unpleasant or a flaw, and is actually part of the flavor profile of some grapes and the wines made from those grapes. If the wine is balanced, I rather enjoy these herb qualities in a wine. But sometimes the flavors are harsh or stick out, and sometimes they add to an unpleasant “feels like I’m biting into unripe fruit” quality.
The greenness could be part of the flavor of the grape itself, as I mentioned. It could also be the result of unripe grapes, winemaking practices that leave a wine out of balance, or, as you mentioned, it could be the result of some stem influence.
Now, some winemakers like a bit of stem. You may have heard of “whole cluster” fermentation, where entire bunches of grapes are fermented, not just the juice or crushed grapes. I know some winemakers who wait until the stems themselves get ripe—they turn brown—before picking and fermenting. When done right, it can add both a spicy complexity and a better texture to the wine. But if someone uses unripe stems, the wines can take on what I’d call an herbal or even vegetal quality. Again, it depends on how well these flavors are integrated.
Are stems needed for aging? I’m sure you could find winemakers who say that whole-cluster fermentation is important to their wines’ profile, including their ability to age. But it’s unfair to characterize whole-cluster fermentation more broadly than that. It’s simply a tool winemakers can use if they wish. There are plenty of wines that have the stuffing to age that don’t employ this method, and plenty that did that have a short life span.
—Dr. Vinny