Planting a Vineyard – Site Selection
Selecting a great site is the single most important factor when planting a vineyard. Its variable characteristics need to be sensitively assessed and measured so that appropriate decisions can be made on vineyard design. This is even more necessary in English Vineyards where micro-climates and soil types can differ greatly across small areas. So, what makes a good vineyard? Below are some parameters that you should consider if you’re thinking of planting a vineyard.
Climate and Temperature
The UK is a cool climate wine producing country on the limit of ripening grapes for quality wine production. A grapevines phenological development is greatly influenced by air temperature, therefore heat accumulation is measured so that regions or vintages can be easily compared. Historical regional temperature data can be used as a guide to determine a site’s ripening capacity before planting, although adjustments should be made for site specific features such as altitude and wind exposure. Measuring the growing degree days (GDD’S) is one method of assessing heat accumulation and is calculated by subtracting a base number of 10 from the daily average temperature for each day of the growing season (April-October). Typical values to ripen Pinot Noir and Chardonnay is around 1150.
The importance of altitude should not be undervalued when analysing a sites potential. The Quality Wine Scheme states that English PDO wines must be produced from vines grown 220m below sea level. Higher altitudes vineyards tend to be free draining and experience an increase in light concentration which can favour photosynthesis, however vine phenology is governed by temperature and as average temperatures decrease with altitude so does ripening capacity. Lower altitude vineyards enjoy warmer temperatures that aide yields and ripening but they can also experience increased humidity which can increase frost risk and disease incidence. Vineyards situated at 30-100m are considered most favourable for UK wine production.
In the UK, southern facing slopes are most desirable as they receive the majority of sunlight throughout the day resulting in higher temperatures. Slopes also allow for better drainage and airflow which helps mitigate against damage from frost and diseases, although wind chill experienced from increased exposure can lower temperatures. Sloped soils tend to have a lighter structure making them prone to erosion which can affect nutrient availability, and if not properly managed this can impact establishment and yields. This doesn’t mean all vineyards should be on a south facing slope or that you shouldn’t plant a vineyard on flat ground, but you must be aware that compromises on varieties and wine styles may need to be made for the vineyard to be successful.
Soil is one of the most talked about vineyard characteristics yet it is also the least understood. To date, Cranfield University has identified over 700 hundred different soil types in the UK. In vineyards we’re mostly interested in soil texture (proportion of sand, silt and clay) soil structure and soil health as these are the main characteristics which can greatly influence how a vineyard is planted. Analysing a sites soil (top soil and sub soil) is a vital part of establishing a vineyard and should be completed across multiple locations when assessing site viability. It is often said that vines need poor soil to grow well but in a cool climate well managed, healthy soil with good structure and balanced nutrient availability is key to making a vineyard successful.