Article Summary
This blog details the stressful, high-stakes period from grape maturation to the initial creation of wine, focusing on the critical decision of when to harvest based on precise chemical balances in the fruit. The physical labour of the harvest immediately gives way to the controlled science of the cellar, where meticulous monitoring of fermentation is required to successfully transform the fruit into the first iteration of your finished product.
If Part 1 was the foundation, Part 2 is the frantic, high-stakes construction phase. You’ve successfully navigated the silent, existential threat of three years’ patience. The vines are mature, the canopy is managed, and the fruit is finally hanging heavy. You’ve earned yourself a brief, perfect moment of calm.
Now, take a deep breath. Because the next 4 to 6 weeks are where all the sweat, money, and screaming at deer either pays off or dissolves into a puddle of acetic acid.
Phenolic Panic and the Point of No Return
The countdown begins the moment the grapes enter véraison—the magical phase when the green, hard berries soften and change colour. Everything speeds up, and your daily routine shifts from pruning to relentless tasting and testing, often involving samples taken 3 times per week across your vineyard blocks.
The Brix, the pH, and the Fear
Forget the romance of biting into a perfectly ripe grape. Now, you’re a triage nurse with a refractometer and a pipette. You are searching for that sweet (literally) spot where the sugars (Brix), the total acidity (TA), and the pH are in perfect alignment.
| Metric | Target Range (Typical) | Consequence of Being Off-Target |
| Brix (Sugar) | 22.5 to 25.5 | Below 20: Thin wine, alcohol approx. 11%. Above 26: Boozy monster, alcohol approx. 15%+. |
| pH (Acidity) | 3.2 to 3.5 (Whites) 3.5 to 3.8 (Reds) | Above 4.0: Flat, spoilage risk; requires up to 2 g/L tartaric acid adjustment. |
| Total Acidity (TA) | 6 to 9 g/L (as tartaric acid) | Too low TA for the pH results in flabby wine; too high requires costly de-acidification. |
| Phenolic Maturity | Seeds are dark brown and crunchy | If green and bitter, tannins will be harsh; risks adding 50 ppm of SOâ‚‚ for stability. |
You are constantly making a terrible gamble against the weather. Do you wait three more days for better phenolics, risking a devastating hail storm (a loss of 100% of the crop in hours) or an unseasonal downpour that will dilute everything, potentially dropping your Brix by 1 to 2 points? The decision is yours, and the consequences are immediate.
The Harvest: The Controlled Chaos
You’ve made the call. The date is set. The atmosphere shifts from serene farm life to a highly-caffeinated, physically brutal military operation that often runs for 18 to 24 hours straight.
Manual vs. Mechanical: The Great Debate
The first question is: who is picking?
- The Romantic/Expensive Option (Manual): A crew, averaging 10-15 people per hectare, snips clusters into bins, usually at a rate of 1 to 2 tonnes per hour per team. This is essential for top-tier, delicate wines. It costs £150 to £400 per tonne, compared to machine harvesting.
- The Efficient/Brutal Option (Mechanical): A colossal, multi-tonne machine straddles the row and aggressively shakes the grapes off the vine. It’s fast and cost-effective, harvesting up to 10 tonnes per hour. The cost can be as low as £40 to £80 per tonne.
The Race to the Press
Once picked, the clock is ticking. You must get the fruit to the winery and process it immediately while it’s still cool—ideally keeping the fruit temperature below 15 degrees C.
- The Weigh-In: Every lorry is weighed, logged, and sampled. A typical yield might be 3 to 8 tonnes per acre, which must be tracked against budget forecasts.
- The Crusher/Destemmer: For red wine, the grapes are separated from their stems. For white wine, the press separates the juice. For every 1,000 kg of grapes, you typically get 700 to 800 litres of must (grape juice).
The Transformation: Winemaking is Chemistry, Not Magic
You’ve got your must in a tank—an expensive, stainless steel tank that you’ve scrubbed obsessively clean. This is where the science really takes over.
Yeasts, Nutrients, and The Big Sleep
You have to decide on yeast. If inoculating, you add commercial Saccharomyces cerevisiae at a rate of about 20 g per 100 L. You check nutrients like Yeast Assimilable Nitrogen (YAN), targeting a minimum of 150 ppm.
The yeast begins consuming the sugar, converting it into ethanol and carbon dioxide. Fermentation must be temperature-controlled, typically held between 28 degrees C and 32 degrees C for reds, and cooler, around 12 degrees C to 18 degrees C, for whites. The process takes anywhere from 7 to 20 days.
- Punch Downs (Pigeage) and Pump Overs (Remontage): For red wine, the cap (skins and seeds) forms. You must break this cap regularly, often 2 to 3 times per day, to ensure extraction of colour and tannin. This labour can involve moving thousands of pounds of grape solids daily.
Pressing Off and Settling In
When the fermentation reaches the desired dryness (usually less than 2 g/L residual sugar), you press off the new wine from the skins. The raw, cloudy, high-acid wine is then transferred to a holding tank or into expensive French oak barrels, which can cost £800 to £1,200 each.
A Year of Patience, Again
The vineyard outside is dropping its leaves, but the work has only moved indoors.
- You monitor the Malolactic Fermentation (MLF), which is crucial for red wines, often taking 3 to 6 months.
- You top up barrels (the “angels’ share”) every 1 to 2 weeks, compensating for the 2% to 5% of volume loss per year due to evaporation.
- Finally, you blend and bottle your masterpiece, after potentially 6 to 24 months of ageing.
You’ve not just made a beverage; you’ve bottled a year of your life, your science, and your very stubborn will. The wine is made, but the real test is still ahead, check out part 3 for more!