We hear about whole cluster fermentation more and more each year. Perhaps you’ve also heard how they can taste “stemmy.” So, why is whole cluster so popular and how does it affect the quality of wine?

What is Whole Cluster Fermentation?

Whole cluster refers to making wine with whole bunches of grapes including their stems. (Normally, grapes go into a destemming machine before fermenting.) What might surprise you is wine was made this way for ages—before destemming machines were invented it was impractical to pluck off individual grapes by hand.

Whole Cluster Fermentation destemmed illustration by Wine Folly

Whole Cluster Fermentation destemmed illustration by Wine Folly

Before there were destemming machines, grape bunches were fermented stems and all!

Why Ferment Whole Bunches?

Why ferment whole clusters? To make wines more complex by weaving in spicy and herbal flavors, to add candied and airy fruit notes, to add tannin structure, and to smooth out high acidity.

Beyond green and herbal notes, the stems impart a whole range of aromatic and textural qualities into wines. So, if whole cluster “stemmy” flavors have turned you off before, you might try them again. They actually help make many wines taste great.

Let’s take a look at some common grape varieties that use whole clusters in the fermentation.

Whole cluster stemmy flavors in wine - illustration by Wine Folly