Vineyard Strategies & the 2009 Growing Season

By Philippe Pessereau, Director of Vineyard Operations

Due to our inherent status as vignerons, we are constantly having to deal with the tribulations of Mother Nature. More specifically, due to our location in a Mediterranean climate where it almost never rains from April to October, and temperatures can push the thermometer bulb quite high during that period, we need to take into account yearly precipitations.

In addition, since grapevines depend on certain water needs for growth and especially evapotranspiration, it is crucial that we consider these parameters in our farming approach in order to achieve appropriate vine development for optimum fruit quality.

We monitor annual rainfall for each ranch yearly and we also measure plant water stress during the growing season. At the beginning of the rainy season in October, we track precipitation through the following season (through May) to paint a picture of the soil moisture status.

Then around bloom time (mid to late May), we start measuring vine water stress in specific areas in each vineyard. Such measurements are usually repeated weekly and enable us to determine when, where and in which quantity we need to irrigate.

In general, if we have a normal rainy season (30-37 inches based on site) we will not need to irrigate early, but if precipitation is sparse we will need to apply water earlier. These decisions also depend on the soil characteristics in each vineyard. Well-drained soils (rocky, gravelly, sandy, elevated or shallow) will tend to have a drier soil profile earlier than less well drained soils (clay, hardpan and deep).

Thus far (in the 08-09 season), we have received from 60% to 86% of our average rainfall, depending on the site. In most cases, we have seen similar or better rainfall than the 07-08 season.

Spring Valley in April of this year after the winter rains

Besides observing rainfall and plant water stress, we also have a panoply of tools at our disposal to maintain adequate soil moisture during the growing season. We apply soil amendments, use more sustainable practices and tailor our soil management according to the weather.

For example, in the fall we broadcast lime, gypsum, dolomite, and compost depending on the site requirements. This is done to maintain proper soil structure for better drainage, aeration and nutrition levels. We also plant cover crops within vine rows to bring organic matter and natural nitrogen to the soil, and also attract beneficial insects. The incorporation of compost and cover crops keeps proper levels of organic matter for humus soil build up. An added benefit of this organic matter is its capacity to absorb water like a sponge. When combined with calcic amendment, the result is well aerated, moist soil which in turn serves to boost soil microbial life activity. Such soils are teeming with life and provide the foundation for robust healthy vines which in turn are able to withstand weather changes and pest pressure.

We also time our soil cultivation to not only incorporate cover crops in the spring but to activate soil moisture and thus delay the need for irrigation. We firmly believe in feeding and nourishing the soil so that vines have nutrients at their disposal when needed. Moreover, via cultivation, we force vine roots to descend and explore deeper soil profiles where there is more soil moisture available later on in the growing season.

Since working with soil takes time, we supplement vine nutrition and provide stress relief using biodynamic teas and decoctions made from plant extracts and delivered as foliar sprays.