Vineyard Site Selection

Introduction

Vineyard site selection is among the most consequential decisions in viticulture—a choice that cannot be easily reversed and will influence wine quality for decades or centuries. The interaction of climate, soil, topography, and mesoclimate determines which varieties can succeed, what wine styles are possible, and the ultimate quality potential of a site. For enologists, understanding site selection principles is essential because vineyard potential fundamentally constrains winemaking possibilities. This guide examines the key factors in site assessment and provides frameworks for evaluating vineyard potential.

Climate Assessment

Macroclimate Analysis

Growing Degree Days (GDD): The Winkler Scale (base 10°C) categorizes climates:

Region	GDD	Suited Varieties
I	<1,390	Pinot Noir, Chardonnay, Riesling
II	1,390-1,670	Cabernet, Merlot, Sauvignon Blanc
III	1,670-1,950	Zinfandel, Syrah, Sémillon
IV	1,950-2,220	Grenache, Mourvèdre, hot-climate varieties
V	>2,220	Table grapes, raisins

Calculating GDD:

Sum of (daily mean temperature - 10°C) for days >10°C
April 1 - October 31 (Northern Hemisphere)
October 1 - April 30 (Southern Hemisphere)

Limitations: GDD alone insufficient; consider diurnal variation, precipitation, humidity.

Temperature Considerations

Mean Temperature Analysis:

Growing season average
Warmest month mean
Ripening period temperatures

Diurnal Temperature Range:

Large swing (15-20°C): Acid retention, aromatic preservation
Small swing (<10°C): Rapid ripening, lower acid

Frost Risk:

Spring frost: Crop loss potential
Frost-free period length
Cold air drainage assessment

Heat Spike Analysis:

Days >35°C
Extreme heat events
Photosynthesis shutdown risk

Precipitation Patterns

Annual Rainfall:

Total amount
Distribution (growing season vs. dormant)
Irrigation requirements

Critical Period Moisture:

Flowering: Moderate preferred
Véraison-harvest: Dry preferred
Post-harvest: Varies

Humidity:

Disease pressure implications
Maritime vs. continental

Sunshine Hours

Total Sunshine:

Growing season hours
Photosynthesis potential
Phenolic development

Cloud Cover Patterns:

Morning fog (can be beneficial)
Afternoon clouds (heat relief)

Soil Assessment

Physical Properties

Texture:

Texture Class	Water Retention	Drainage	Vigor
Sand	Low	Excellent	Low
Loam	Moderate	Good	Moderate
Clay	High	Poor	High-moderate
Gravel	Very low	Excellent	Low

Depth:

Root zone potential
Water reservoir capacity
Target: >60 cm minimum; >100 cm preferred

Drainage:

Surface drainage (slope)
Internal drainage (soil structure)
Water table depth

Structure:

Aggregation
Compaction layers
Root penetration ability

Chemical Properties

pH:

Optimal: 5.5-7.5 (variety-dependent)
Extreme pH: Nutrient lockout

Organic Matter:

Nutrient cycling
Water retention
Microbial activity

Nutrient Status:

N, P, K levels
Micronutrients
Baseline for amendment planning

Cation Exchange Capacity (CEC):

Nutrient retention ability
Higher in clay, organic matter

Limestone/Calcium Carbonate:

Active limestone (vine stress)
Rootstock selection implications

Soil Mapping

Assessment Methods:

Soil pits (detailed characterization)
Auger samples (spatial coverage)
Electromagnetic survey (EM38)
Resistivity mapping
Remote sensing

Variability Assessment:

Map soil boundaries
Identify management zones
Plan block delineation

Topography

Aspect (Orientation)

Northern Hemisphere:

Aspect	Solar Radiation	Temperature	Suited For
South	Maximum	Warmest	Early varieties, cool regions
Southwest	High	Warm afternoon	Most varieties
Southeast	Moderate	Morning warmth	Aromatic varieties
East	Moderate	Cool afternoon	Heat stress avoidance
North	Minimum	Coolest	Too cool (most cases)

Southern Hemisphere: Reverse (North = warmest)

Slope

Degree of Slope:

Slope	Characteristics	Implications
0-5%	Flat	Mechanization easy; frost risk
5-15%	Gentle	Ideal balance
15-30%	Moderate	Good drainage; some difficulty
>30%	Steep	Heroic viticulture; erosion risk

Benefits of Slope:

Air drainage (frost reduction)
Water drainage
Soil erosion (challenge)
Solar radiation increase

Elevation

Temperature Effect: ~0.6°C cooler per 100m elevation gain

Applications:

Climate change adaptation (higher = cooler)
Diurnal variation often greater
UV radiation higher

Air Drainage

Cold Air Movement:

Dense cold air flows downhill
Pools in valleys/depressions
Avoid frost pockets

Assessment:

Topographical analysis
Historical frost records
Temperature monitoring

Water Resources

Water Availability

Sources:

Surface water (rivers, ponds)
Groundwater (wells)
Municipal/district water
Rainfall (dry farming)

Rights and Allocation:

Water rights assessment
Allocation security
Cost analysis

Irrigation Requirements

Calculation Factors:

ETo (reference evapotranspiration)
Crop coefficient (Kc)
Precipitation (effective)
Soil water-holding capacity

Approximate Requirements:

Full irrigation: 400-800 mm/year
Deficit irrigation: 150-300 mm/year
Dry farming: Sufficient rainfall or deep roots

Water Quality

Testing Requirements:

Salinity (EC)
Sodium (SAR)
Chloride, boron
pH
Pathogens (if relevant)

Impact: Poor water quality limits viability

Risk Assessment

Frost Risk

Assessment Methods:

Historical records
Temperature monitoring (min/max)
Topographical analysis
Neighboring vineyard experience

Mitigation Options:

Site selection (avoid frost pockets)
Wind machines
Sprinkler systems
Smudge pots/heaters

Hail Risk

Assessment: Regional historical data

Mitigation:

Hail netting (expensive)
Insurance
Site diversification

Wind Exposure

Impacts:

Vine damage
Spray drift
Cooling effect (can be positive)
Desiccation

Assessment: Local observation; regional data

Mitigation: Windbreaks; site design

Disease Pressure

Site Factors:

Humidity (fog, maritime)
Air circulation
Historical disease records
Neighboring vineyard health

Pest Presence

Assessment:

Regional pest records
Phylloxera presence
Nematode testing
Virus testing

Fire Risk

Increasingly Important:

Regional fire history
Fuel load assessment
Smoke taint risk
Insurance implications

Economic Factors

Land Cost

Considerations:

Purchase price
Lease options
Development costs
ROI projections

Infrastructure

Required Elements:

Road access
Power availability
Water infrastructure
Buildings (existing or needed)

Labor Availability

Assessment:

Local workforce
Seasonal labor access
Wage rates
Mechanization potential (terrain)

Market Access

Considerations:

Distance to winery
Transportation costs
Direct sales potential (if applicable)

Site Evaluation Protocol

Phase 1: Desktop Analysis

Climate data: GDD, rainfall, extremes
Topographical maps: Slope, aspect, elevation
Soil surveys: Existing data review
Historical records: Agricultural history, weather
Regulatory review: Zoning, water rights, land use

Phase 2: Field Assessment

Soil sampling: Pits and auger samples
Water assessment: Sources, quality, quantity
Microclimate monitoring: Install data loggers
Vegetation survey: Indicator species
Neighboring vineyards: Site visits, interviews

Phase 3: Analysis and Decision

Data compilation: Integrate all information
Variety matching: Which varieties suited?
Risk assessment: Major risks identified
Economic modeling: Projected costs and returns
Decision: Proceed, modify plans, or reject

Quality Potential Assessment

Terroir Indicators

Positive Signs:

Well-drained soils
Moderate vigor potential
Good air drainage
Appropriate climate match
Water availability
Low disease/pest pressure

Warning Signs:

Heavy, poorly drained soils
Frost pockets
Extreme climate (too hot or cold)
Water scarcity
High disease pressure
Difficult access

Benchmarking

Compare To:

Successful nearby vineyards
Similar terroirs elsewhere
Regional averages

Conclusion

Vineyard site selection requires systematic analysis of climate, soil, topography, water resources, and economic factors. For enologists, understanding site potential is essential because the vineyard sets the quality ceiling for wine production. No amount of winemaking skill can overcome fundamental site limitations, while excellent sites provide the foundation for extraordinary wines. Thorough site assessment is the first step toward sustainable, quality-focused viticulture.

References

Jackson, D.I. & Schuster, D.F. (2001). “Grape Growing and Wine Making.” Alison and Busby. Publisher Link
White, R.E. (2015). “Understanding Vineyard Soils.” 2nd Edition. Oxford University Press. Publisher Link
Gladstones, J. (2011). “Wine, Terroir and Climate Change.” Wakefield Press. Publisher Link

Last Updated: January 10, 2026
Research Grade: Technical reference
Application: Vineyard establishment, site evaluation, investment decisions