Viticulture | 🍇 From Berry to Harvest Quality

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• Explain explain how canopy management changes the environment around vine and fruit.
• Analyse a canopy for density, airflow, light interception and crop load
• Evaluate a canopy decision using growth, fruit exposure, disease risk and grape quality.

Westover Viticulture – Canopy Management

🌱 How does berry develop for harvest?

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Understanding how grape development determines harvest quality

The production of quality grapes depends on understanding how the grapevine develops, how berries ripen and how environmental and management factors influence the final crop.

For a vineyard grower, harvesting is not simply a matter of waiting until grapes look ripe. It involves monitoring berry development, assessing sugar and acidity, observing flavour and colour changes, and deciding when the crop meets the requirements of its intended use.

The aim is to produce healthy, suitably ripened grapes that meet the required specification for the wine being made.

1. Stages of Berry Development

Grape berries develop through a series of recognisable stages, from fruit set through to harvest.

Fruit Set

Following flowering and successful fertilisation, the ovary develops into a small green berry. Not every flower produces a grape, and the number of berries that develop influences the eventual crop size.

Berry Growth

The berries increase in size as they accumulate water and nutrients. They are initially firm, green and relatively high in organic acids. Seeds develop inside the berries.

Veraison

Veraison marks the beginning of ripening and is an important turning point in berry development.

• White varieties begin to soften and may become more translucent or yellow-green.
• Red varieties begin developing their characteristic red, purple or blue colour.
• Sugar accumulation increases.
• Acidity begins to decline.

Ripening

The berries continue to soften and accumulate sugars. Acidity changes, colour develops further and flavour and aroma compounds become more pronounced.

Harvest

The grapes are picked when the grower considers them suitable for their intended wine style, market and production specification.

2. What Changes Inside a Grape During Ripening?

Ripening involves a series of important chemical and physical changes within the berry. These changes influence the eventual taste, balance, alcohol potential and style of the wine.

Sugar accumulation

As grapes ripen, they accumulate sugars, mainly glucose and fructose.

These sugars are produced through photosynthesis in the leaves and transported around the vine, eventually accumulating in the berries.

Sugar concentration is important because it determines the potential alcohol content of the finished wine.

Sugar levels are commonly measured using a refractometer and expressed as degrees Brix (°Bx).

Illustrative examples:

• 16° Brix – relatively low sugar concentration.
• 20° Brix – higher sugar concentration.
• 24° Brix – higher sugar concentration and greater potential alcohol.

The appropriate sugar level depends on grape variety, growing conditions and intended wine style.

Acidity

Grapes naturally contain organic acids, particularly:

• Tartaric acid: One of the main acids found in grapes and wine.
• Malic acid: An important organic acid that generally decreases during ripening.

As grapes ripen, acidity usually decreases.

Acidity contributes to the freshness, crispness and balance of wine. It also influences wine stability and flavour.

If grapes are harvested too early, acidity may be high and flavours underdeveloped. If harvested too late, acidity may become too low, resulting in wine that lacks freshness.

pH

pH is another important measurement used by growers and winemakers.

It indicates the acidity of grape juice:

• Lower pH means greater acidity.
• Higher pH means lower acidity.

pH and titratable acidity measure different things. Two grape samples can have similar titratable acidity but different pH values.

Monitoring both provides a better understanding of grape chemistry.

Colour development

Colour development is particularly important in red grape varieties.

During veraison, pigments called anthocyanins begin accumulating in the grape skins. These pigments produce the red, purple and blue colours associated with red wine varieties.

White grape varieties undergo different colour changes, often developing yellow-green or golden tones as they ripen.

Flavour and aroma development

As ripening progresses, flavour and aroma compounds develop within the berries.

Depending on the grape variety and growing conditions, these may contribute characteristics such as:

• Citrus and green fruit.
• Apple and pear.
• Stone fruit.
• Tropical fruit.
• Floral and more complex ripe fruit aromas.

The development of these compounds is important when determining the suitability of grapes for different wine styles.

3. Monitoring Grape Quality

Growers cannot rely on appearance alone to decide when grapes are ready to harvest.

Regular sampling and testing help establish how the crop is developing and whether it is approaching the required specification.

Three particularly important measurements are Brix, pH and titratable acidity.

Brix – measuring sugar

A refractometer measures the soluble solids in grape juice, primarily sugars.

The result is expressed as degrees Brix.

As grapes ripen, Brix generally increases as sugars accumulate in the berries.

pH – measuring acidity

A pH meter measures the acidity of grape juice.

Monitoring pH helps growers and winemakers assess the chemical balance of the fruit and its suitability for the intended wine.

Titratable acidity – measuring total acid

Titratable acidity measures the total amount of acid that can be neutralised during a titration test.

Results are usually expressed in grams per litre (g/L), with the reporting acid specified.

TA provides useful information about the overall acid concentration of the grapes.

Importantly, these measurements need to be considered together. A high sugar reading does not automatically mean grapes are ready to harvest.

4. Factors Influencing Grape Quality

The quality of harvested grapes is influenced by the interaction between the vine, its environment and the way the vineyard is managed.

Yield and crop load

Crop load refers to the amount of fruit being carried by the vine in relation to its capacity to support that crop.

A vine carrying too much fruit may struggle to ripen the crop fully, particularly when growing conditions are challenging.

Growers manage crop load through:

• Winter pruning.
• Shoot thinning.
• Bunch thinning.
• Canopy management.

The objective is to achieve an appropriate balance between crop production and vine growth.

Vine balance

A balanced vine has sufficient healthy leaf area to support its crop and maintain healthy growth.

Leaves produce the sugars required for berry development and ripening through photosynthesis.

Too much vegetative growth can create a dense canopy, shading fruit and restricting airflow.

Too little healthy leaf area may limit the vine’s ability to ripen its crop.

Environmental conditions

Environmental conditions influence both the rate of ripening and the final quality of the grapes.

In the UK, weather can be particularly important when deciding harvest timing. Prolonged rainfall, disease pressure or an approaching storm may influence the decision to harvest earlier than originally planned.

Canopy management and fruit exposure

The canopy influences how much light and air reach the grape bunches.

Good canopy management can:

• Improve light distribution.
• Maintain healthy leaf area.
• Improve airflow around bunches.
• Reduce prolonged moisture around fruit.
• Reduce disease pressure.
• Support more consistent ripening.

Canopy management is therefore not simply about keeping vines tidy. It directly influences the condition and quality of the harvested crop.

5. Determining Harvest Readiness

Harvest is one of the most important decisions a vineyard manager makes.

Picking too early or too late can affect the quality, style and value of the finished wine.

The decision needs to consider the intended product, the condition of the grapes and the practical requirements of harvesting.

Calatroni Vini

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What should a grower consider?

Sugar levels

Are the grapes at an appropriate sugar concentration for the intended wine style?

Acidity and pH

Is there sufficient acidity to maintain freshness and balance?

Flavour development

Do the grapes have the expected flavour and aroma characteristics?

Berry condition

Are the berries healthy, intact and free from significant disease or damage?

Crop uniformity

Are grapes ripening consistently throughout the vineyard block?

Weather and harvesting conditions

Is there a suitable opportunity to harvest before conditions deteriorate?

Winery or market specification

Does the crop meet the requirements of the intended buyer or winery?

Different wines – different harvest decisions

Not all grapes are harvested at the same stage of ripeness.

English Wine Guide: Sparkling & Beyond | Sommy

Sparkling wine

Grapes are often harvested at lower sugar levels and higher acidity to maintain freshness and produce a suitable base wine.

ripe chardonnay grapes hanging on vine in vineyard at harvest time with blurred background and copy space

Still white wine

Harvest timing depends on the desired balance of acidity, sugar and flavour development.

GRANDE SÉLECTIONPINOT NOIR > Antonin RODET

Red wine

Growers may allow additional ripening to develop colour, flavour and tannin maturity.

Typical grapes with botrytis cinerea for sweet wines, Sauternes, Bordeaux, Aquitaine, France

Sweet wine

Grapes may be left longer or harvested under specific conditions to achieve the required sugar concentration and flavour characteristics.

There is no single perfect harvest measurement for every grape variety or wine style. Harvest decisions must reflect the intended product and the specification required by the winery.

6. From Vine Biology to Commercial Crop Quality

The production of quality grapes depends on all the biological processes and management decisions that take place throughout the growing season.

Each part of the vine contributes to the final crop:

Grapes | PDF

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• The vine structure provides the framework for growth and fruit production.
• The annual cycle determines when growth, flowering, fruit development and dormancy take place.
• Buds and canes provide the potential for new shoots and fruiting growth.
• Flowering and fruit set establish the developing crop.
• Photosynthesis and respiration provide the energy and resources needed for growth.
• The root system supplies water and nutrients.
• The canopy and crop load influence the vine’s ability to develop and ripen its fruit.
• Berry ripening determines the sugar, acidity, colour and flavour characteristics of the harvested grapes.

Ultimately, the vineyard technician needs to understand how these processes interact.

The ability to monitor the crop, interpret information and make appropriate management decisions is what turns an understanding of vine biology into effective commercial vineyard management.

The key principle

Growing grapes is about more than producing a crop. It is about producing grapes that meet a specific quality requirement.

Understanding the vine allows the grower to manage its development. Monitoring the berries allows the grower to assess quality. Combining both allows informed decisions about harvest timing.