Wine on the farm, step by step
Interactive lesson: from harvest to bottle — sugar and acid, CO₂ in the cellar, white and red wine, sulphite, racking and bottling.
Free sample Chapters 1 and 2 (8 steps) are free. The full lesson comes with the Wine on a small farm module. Already bought? Unlock
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The whole lesson as text
1. Picking by sugar
Wine quality can't be fixed in the cellar.
- Measure from veraison — Use a refractometer every 5–7 days: a drop of juice from 10–20 berries from different bunches and both sides of the vine.
- Signs of ripeness — Sugar stops rising over two readings in a row, the seeds are brown and the bunch stalk starts turning woody. Roughly 19–22 °Brix for white, 21–24 for red.
- Dry morning, shallow crates — Pick on a dry, cool morning, into crates of 15–20 kg. Grapes picked in the midday sun start an uncontrolled fermentation sooner.
- Sort, process today — Put bunches with grey mould and sour rot in a separate bucket: they don't go into the wine. Process the grapes the same day.
Why: Ripe, sound grapes make good wine with little effort. Unripe or rotten grapes need a lot of correcting and the wine is still poor. 1 L of wine takes roughly 1.3–1.5 kg of grapes.
- Total acid in ripe grapes is roughly 6–9 g/L for white and 5–7 g/L for red. In a warm year it drops fast, so pick earlier.
- Wasps and hornets are everywhere at harvest. Anyone with an allergy carries the medicine their doctor prescribed.
2. The cellar and CO₂
Fermenting 100 L of must gives roughly 5 m³ of carbon dioxide.
- Ventilation — While the wine ferments, keep the cellar door and windows open, with a fan drawing air out near the floor.
- Head above the rim — Don't lean your head into the vat. Punch down the cap with a long-handled plunger, standing upright.
- A candle is no protection — It goes out only when the CO₂ is already deadly. For a cellar with more than a few hundred litres, buy a CO₂ detector.
- Never alone — During fermentation, go into the cellar in pairs.
Why: CO₂ is heavier than air, invisible and odourless. It collects above the skins in the vat and near the floor. At 8–10 % in the air a person passes out within a few breaths.
- If someone collapses, don't go in after them. Call 999 or 112 (UK, IE) or 911 (US, CA) and blow air in with a fan from outside.
- Children and animals stay out of the cellar while the wine is fermenting.
3. White wine · Locked
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4. Red wine on the skins · Locked
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5. Racking and topping up · Locked
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6. Faults and bottling · Locked
Buy the Wine on a small farm module and you get the PDF to download and print, plus lifetime access to this interactive lesson: all 6 chapters, 24 steps.