Glera

Summary

Glera is the grape variety responsible for Prosecco, one of the world’s most commercially successful sparkling wines. With approximately 30,000 hectares under cultivation (primarily in Veneto and Friuli Venezia Giulia), Glera-based Prosecco has become Italy’s most exported wine. The variety was officially renamed from “Prosecco” to “Glera” in 2009 to protect the Prosecco designation geographically, linking the wine name to the village of Prosecco near Trieste rather than to the grape. Glera produces wines characterized by delicate floral and fruit aromatics (green apple, pear, white flowers), moderate acidity, and light body. The variety is predominantly vinified as sparkling wine using the Charmat (tank) method, which preserves its fresh, fruit-forward character better than traditional method bottle fermentation. While most Prosecco is produced for immediate consumption, the steep hillside vineyards of Conegliano-Valdobbiadene DOCG demonstrate the variety’s capacity for more complex, terroir-expressive wines.

Identity & Synonyms

Official Name: Glera
VIVC Database: VIVC Entry #4668
Prime Name: GLERA (VIVC)
Berry Color: BLANC (White/Green-yellow)

Synonyms:

• Prosecco (historical name; now protected geographical indication)
• Glera Tondo (round-berried biotype)
• Glera Lunga (long-berried biotype)
• Serprina or Serprino (Colli Euganei)
• Prosecco Tondo
• Prosecco Lungo

Name Change (2009): The variety was officially renamed from “Prosecco” to “Glera” by Italian authorities to establish Prosecco as a protected geographical designation (DOC/DOCG) rather than a varietal name. This prevents production of “Prosecco” wine outside the designated Italian regions.

Related Varieties:

• Glera Lunga: Distinct biotype with elongated berries; permitted in DOC/DOCG but rarely used
• Bianchetta Trevigiana: Historically confused with Glera; genetically distinct

Genetic Origin / Pedigree

Origin: Veneto/Friuli Venezia Giulia border region, northeastern Italy

Parentage:

• Unknown - Ancient variety with no confirmed parents
• DNA analysis suggests northeastern Italian origin
• Likely cultivated in the region for several centuries
• Name possibly derived from the village of Prosecco (Trieste province)

DNA Verification: No confirmed parentage; genetic studies confirm distinctiveness from other northeastern Italian varieties.

Historical Documentation: First documented references appear in the 18th century, though the variety was likely cultivated earlier. The sparkling wine style developed primarily in the 20th century.

Clonal Diversity: Limited diversity; main clones selected for:

• ISV-ESAV 10: Balanced yield and quality
• ISV-ESAV 14: Aromatic intensity
• VCR clones: Various quality selections

Global Distribution

Total Area Planted: ~30,000 hectares (almost exclusively in Italy)

Italian Distribution (ha):

1. Veneto - ~25,000 ha
   • Treviso province: ~18,000 ha (core Prosecco region)
   • Conegliano-Valdobbiadene DOCG: ~8,400 ha
   • Asolo DOCG: ~2,000 ha
2. Friuli Venezia Giulia - ~4,000 ha
   • Includes original Prosecco village area (Trieste province)

International Plantings: Minimal; DOC/DOCG regulations restrict “Prosecco” labeling to Italian production. Some Glera planted in:

• Australia - ~100 ha (labeled as Glera, not Prosecco)
• Brazil - Minor plantings
• USA - Experimental

Planting Trends:

• Dramatic expansion: Prosecco vineyard area has more than doubled since 2009
• DOC expansion: Prosecco DOC (2009) created vast production area
• Hill vs. plain: Quality concerns as production expands to flatter, more fertile land

Viticulture

Phenology:

• Bud burst: Medium
• Flowering: Medium
• Véraison: Medium to late
• Harvest: Late (mid-September to mid-October)
• Growing season: 175-195 days from bud burst to harvest

Vigor: High - naturally vigorous; requires restrictive management for quality.

Fertility: Very high - 2.0-3.0+ clusters per shoot; crop thinning essential for quality.

Typical Yield:

• Conegliano-Valdobbiadene DOCG: 13,500 kg/ha (~94.5 hl/ha as still wine base)
• Asolo DOCG: 13,500 kg/ha
• Prosecco DOC: 18,000 kg/ha (higher yields permitted)
• Quality-focused hillside: 8,000-11,000 kg/ha

Disease Sensitivities:

• Botrytis bunch rot: HIGH susceptibility (tight clusters, thin skins)
• Downy mildew (Peronospora): HIGH susceptibility
• Powdery mildew (Oidium): Medium-high susceptibility
• Sour rot: Medium susceptibility

Climate Fit:

• Optimal: Cool to moderate continental/Mediterranean transition climates
• Growing Degree Days: 1,800-2,400 GDD (base 10°C)
• Benefits from warm days and cool nights for aromatic development
• Excessive heat reduces acidity and aromatic freshness

Soil Preferences:

• Calcareous marl (Conegliano-Valdobbiadene hills): Classic terroir; mineral expression
• Clay-limestone: Structured, aromatic wines
• Alluvial plains (DOC flatlands): Higher yields, simpler wines
• Hillside vs. plains: Significant quality difference based on site

Training Systems:

• Sylvoz: Traditional pergola-style; common in DOC areas
• Cappuccina: Modified Sylvoz
• Guyot: Increasingly used for quality; better exposure
• Bellussera: Historical ray-pattern training

Enology

Typical Must Parameters at Harvest:

• Sugar content: 17-20 °Brix (sparkling base wine; lower than still wine)
• pH: 3.0-3.3 (moderate-high acidity)
• Titratable acidity: 6.0-8.0 g/L (as tartaric acid)
• Potential alcohol: 10.5-12.0% ABV (base wine)

Sparkling Wine Production (Charmat/Martinotti Method):

The Charmat method (also called Martinotti method or tank method) is the standard production method for Prosecco:

Primary Fermentation:

• Cool fermentation (14-18°C) in stainless steel
• Preserves delicate aromatics
• Complete fermentation for dry base wine

Secondary Fermentation (Prise de Mousse):

• Conducted in pressurized stainless steel tanks (autoclaves)
• Duration: Minimum 30 days (DOCG); 30+ days typical
• Temperature: 14-18°C
• Pressure develops naturally from CO₂
• “Lungo” fermentation (60-90+ days) for premium wines

Charmat vs. Traditional Method:

• Charmat preserves primary fruit aromatics
• Traditional method (bottle fermentation) adds yeast autolysis character
• Prosecco regulations permit only Charmat method for DOC/DOCG
• Col Fondo (ancestral method) is alternative permitted style

Sweetness Levels (Residual Sugar):

• Brut Nature: 0-3 g/L
• Extra Brut: 0-6 g/L
• Brut: 0-12 g/L (most common)
• Extra Dry: 12-17 g/L (traditional Prosecco sweetness)
• Dry: 17-32 g/L
• Demi-Sec: 32-50 g/L

Pressure Categories:

• Spumante: ≥3.5 bar (fully sparkling)
• Frizzante: 1.0-2.5 bar (semi-sparkling)
• Tranquillo: Still wine (rare)

Col Fondo (Traditional Style):

• Ancestral method; bottle-fermented
• Cloudy; unfiltered; yeast sediment retained
• More complex, less fruit-forward than Charmat
• Growing niche interest

Aging Potential:

• Standard Prosecco: Drink within 1-2 years
• DOCG Rive (single-vineyard): 2-4 years
• Col Fondo: 2-5 years
• Not designed for extended aging: Freshness is the primary quality

Sensory & Chemical Markers

Chemical Composition:

• Total acidity: Moderate-high (6-8 g/L)
• pH: 3.0-3.3 (provides freshness, stability)
• Residual sugar: Variable by style (0-50 g/L)
• Alcohol: 11-12.5% (typical finished sparkling)

Key Aroma Compounds:

• Esters: Isoamyl acetate (pear, banana), ethyl hexanoate (apple)
• Terpenes: Linalool, geraniol (floral, citrus) - moderate levels
• Aldehydes: Hexanal (green apple)
• Higher alcohols: Contribute to fruit character

Sensory Profile:

Standard Prosecco (Brut/Extra Dry):

• Visual: Pale straw with greenish tints; fine, persistent bubbles
• Aromatic: Green apple, pear, white flowers (acacia), citrus, almond
• Palate: Light body, fresh acidity, delicate fruit, soft mousse, clean finish

DOCG Conegliano-Valdobbiadene:

• Visual: Pale to light straw; fine bubbles
• Aromatic: More complex; apple, pear, white peach, wisteria, mineral notes
• Palate: Medium body, vibrant acidity, more structure, saline/mineral finish

Rive (Single-Vineyard DOCG):

• Aromatic: Terroir-specific nuances; greater aromatic complexity
• Palate: More textured; site-specific character; longer finish

Col Fondo:

• Visual: Cloudy/hazy; yeast in suspension
• Aromatic: Bread dough, orchard fruit, more savory
• Palate: Fuller body, more complexity, yeast influence, dry

Common Enological Issues

Botrytis and Harvest Timing

• Cause: High botrytis susceptibility combined with late harvest (September-October) when autumn rains are common in Veneto.
• Risk: Grey rot compromises fruit quality; off-flavors; sorting requirements; laccase activity in must.
• Decision point: Harvest timing critical—balance ripeness against rot pressure; rigorous sorting essential; vineyard monitoring; canopy management for air circulation.

High Yields and Dilution

• Cause: Very high natural fertility combined with DOC regulations permitting 18,000 kg/ha; economic pressure for volume.
• Risk: Dilute, characterless wines; loss of varietal distinction; quality-image damage to category.
• Decision point: DOCG (lower yields) vs. DOC positioning; green harvest for quality; site selection (hillside vs. plains); producer philosophy.

Base Wine Oxidation

• Cause: Light, delicate base wines are susceptible to oxidation during handling and storage.
• Risk: Loss of freshness; browning; premature aging character.
• Decision point: Protective winemaking throughout; inert gas handling; appropriate sulfur dioxide; minimize oxygen exposure; early secondary fermentation.

Fermentation Temperature Control

• Cause: Secondary fermentation in tank generates heat; temperature control critical for aromatic preservation.
• Risk: Loss of delicate aromatics if fermentation too warm; coarse bubble formation.
• Decision point: Temperature-controlled autoclaves essential; fermentation at 14-18°C; monitoring throughout process.

Pressure Stability

• Cause: Bottled under pressure; requires appropriate closure and bottle design.
• Risk: Pressure loss; flat wine; cork failure.
• Decision point: Quality closures (composite cork, crown cap for Col Fondo); bottle specification; storage conditions.

Freshness Loss Post-Bottling

• Cause: Prosecco’s appeal depends on freshness; quality degrades relatively quickly.
• Risk: Stale, oxidized character in aged bottles; consumer disappointment.
• Decision point: Inventory management; “drink young” communication; vintage dating; cold chain maintenance.

Operational Considerations

Harvest timing:

• Late harvest (mid-September to mid-October)
• Balance sugar accumulation with acid retention
• Botrytis monitoring essential—harvest before infection spreads
• Multiple passes may be necessary in affected vintages
• Earlier harvest (lower sugar) acceptable for sparkling base

Must handling:

• Gentle pressing to minimize phenolic extraction
• Clean, aromatic juice priority
• Cold settling at 10-14°C
• Protective handling (inert gas, SO₂)

Primary fermentation:

• Cool fermentation (14-18°C) for aromatic preservation
• Complete fermentation to dry base wine
• Selected yeast strains for aromatic expression
• Duration: 10-20 days

Base wine preparation:

• Clarification and stabilization before secondary fermentation
• Tartrate stability essential (cold stability)
• Blending of lots for consistency (cuvée assembly)
• Filtration before tank transfer

Secondary fermentation (Charmat):

• Autoclave (pressurized tank) preparation
• Sugar and yeast addition (liqueur de tirage)
• Temperature: 14-18°C
• Duration: Minimum 30 days (DOCG requires extended)
• Longer fermentation (“Charmat lungo”) for complexity

Pressure management:

• Target pressure: 5-6 bar for Spumante
• Lower pressure: 1.0-2.5 bar for Frizzante
• Isobaric (pressure-maintained) handling and bottling

Sweetness adjustment:

• Dosage (liqueur d’expédition) after filtration if needed
• Target residual sugar based on style category
• Extra Dry (12-17 g/L) traditionally popular
• Brut (0-12 g/L) increasingly common

Bottling and storage:

• Isobaric bottling to maintain pressure
• Quality closures essential
• Cool storage (preferably 10-15°C)
• Rapid turnover; not intended for aging

Key Regions & Appellations

Conegliano-Valdobbiadene Prosecco Superiore DOCG (Veneto)

Official Regulation: Consorzio Prosecco DOCG

• Varietal requirement: Minimum 85% Glera
• Area under vine: ~8,400 ha
• Geography: Steep hillside vineyards; UNESCO World Heritage (2019)
• Categories: Brut, Extra Dry, Dry; Rive (single-vineyard); Cartizze (grand cru equivalent)
• Cartizze: 107 ha subzone; considered top terroir; sweet style traditional
• Characteristics: Benchmark Prosecco; more complex, mineral, age-worthy than DOC

Asolo Prosecco Superiore DOCG (Veneto)

Official Regulation: Consorzio regulations

• Varietal requirement: Minimum 85% Glera
• Area under vine: ~2,000 ha
• Geography: Hills north of Treviso; distinct from Conegliano-Valdobbiadene
• Characteristics: More structured; slightly different aromatic profile; growing recognition

Prosecco DOC (Veneto & Friuli Venezia Giulia)

Official Regulation: Consorzio Prosecco DOC

• Established: 2009 (major regulatory change)
• Varietal requirement: Minimum 85% Glera
• Area under vine: ~24,000+ ha
• Geography: Large area including plains of Veneto and Friuli
• Yield limit: 18,000 kg/ha (higher than DOCG)
• Characteristics: Wide quality range; volume production; entry-level Prosecco

Prosecco DOC Treviso

Official Regulation: Sub-designation within Prosecco DOC

• Geography: Treviso province only
• Characteristics: Generally higher quality than generic DOC; stricter sourcing

Colli Euganei DOC (Veneto)

Official Regulation: DOC regulations

• Varietal name: Serprino (local name for Glera)
• Characteristics: Still and sparkling; distinct regional expression

Notable Benchmark Producers

Reference Examples (not commercial endorsements):

1. Bisol - Valdobbiadene, Veneto
   Historic producer; Cartizze and Cru bottlings; demonstrates DOCG quality potential; family-owned since 1542.

2. Nino Franco - Valdobbiadene, Veneto
   Primo Franco bottling; benchmark for complex, age-worthy Prosecco; demonstrates terroir expression.

3. Adami - Valdobbiadene, Veneto
   Vigneto Giardino and Rive bottlings; organic production; demonstrates hillside quality.

4. Col Vetoraz - Valdobbiadene, Veneto
   Consistent quality; excellent Cartizze; demonstrates benchmark DOCG style.

5. Sorelle Bronca - Valdobbiadene, Veneto
   Female-led; organic; Particella 68 and Rive bottlings; demonstrates sustainable quality production.

6. Casa Coste Piane - Valdobbiadene, Veneto
   Col Fondo specialist; natural winemaking; demonstrates traditional/ancestral style.

Research & References

• VIVC (2025). “Glera - Vitis International Variety Catalogue.” Julius Kühn Institute. Entry #4668

• Consorzio di Tutela Prosecco DOC (2025). “Disciplinare di Produzione Prosecco DOC.” https://www.prosecco.wine

• Consorzio di Tutela Conegliano Valdobbiadene Prosecco DOCG (2025). “Disciplinare di Produzione.” https://www.prosecco.it

• Calò, A., Scienza, A., & Costacurta, A. (2006). “Vitigni d’Italia.” Edagricole. WorldCat Glera/Prosecco entry.

• Tomasi, D., Gaiotti, F., & Jones, G.V. (2013). “The Power of the Terroir: The Case Study of Prosecco Wine.” Springer. Publisher Link

• UNESCO (2019). “Le Colline del Prosecco di Conegliano e Valdobbiadene - World Heritage List.” https://whc.unesco.org

• Nicolini, G., Larcher, R., Román, T., Ferrazza, M., & Catturano, I. (2009). “Aromatic characterization of Prosecco wines.” Rivista di Viticoltura e di Enologia, 62, 15-27. Journal Link

• Robinson, J., Harding, J., & Vouillamoz, J. (2012). “Wine Grapes.” Penguin Books. Publisher Link Glera entry.

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Last Updated: January 6, 2026
Research Grade: WSET Diploma / Master of Wine level