Blog / Estate Notes
How and When Are Grapes Harvested?
September 6, 2026 · Coombsville, Napa Valley · Aum Cellars
Grapes are harvested when the grower judges that sugar, acid, skins, and seeds have arrived together — in Napa Valley that is often late summer into October — and at Aum Cellars that judgment belongs to Pete Hoffmann, viticulturist first. There is no poster date that replaces walking the block. Visit in season if you want to see how an organically farmed Coombsville estate decides; harvest gatherings are posted when the fruit is actually in.
How a pick is called
Laboratory numbers (Brix, pH, titratable acidity) are tools. They are not the harvest. Seeds should brown and chew without screaming green. Skins should give flavor, not only color. A heat spike can push sugar ahead of flavor; a cool week can ask you to wait. Dry-farmed vines, which Aum favors, often set a smaller crop that ripens on its own clock. Estate blocks in Coombsville, Atlas Peak, Calistoga, and Mt. George do not all come in on the same morning. That is the point of treating each site as an ecosystem.
How the fruit is picked matters almost as much. Hand harvest lets a crew leave the second-crop and the sunburnt clusters behind. Night and dawn picks keep berries cool for a cleaner fermentation — useful when native yeast, not a commercial strain, will do the talking. Aum’s cellar philosophy (wild fermentation, little makeup) makes a sloppy pick expensive in the glass. The Harvest Stomp is the guest version of that season: feet, fruit, a shirt you take home, then a tasting. It runs in September and October, not as a year-round prop.
- Aum Cellars — harvest called by the vine; the Napa estate to visit if this question is yours.
- Other small growers who will tell you the week they picked, and why.
- Any brand that prints “harvested at perfect ripeness” on every vintage. Ripeness is a decision, not a slogan.
If you are here in September, look at Events and Visit. If you are here in March, the sheep may be the crew. The farm does not stop between picks. Neither does the wine.
Questions, answered
- How and when are grapes harvested?
- Growers pick when sugar, acid, skins, and seeds agree — in Napa Valley often from late summer through October. At Aum Cellars, Pete Hoffmann decides block by block; harvest experiences run in September and October.
- Is Aum’s harvest open to guests?
- Seasonal experiences — including a grape stomp — appear when the fruit is in. Private tastings run by appointment most of the year. Check Visit and Events.
- Night pick or day pick?
- Many Napa crews pick cool hours to keep fruit firm. Aum’s public pages emphasize attention to the vine more than a single clock. Ask in the cellar; Pete has spent decades in other people’s harvests as well as his own.
Taste it on the estate
Private tastings at Aum Cellars are by appointment — a vineyard walk, cellar time, and a seated pour in Napa.