Growing Grapes in NS

Climate

Nova Scotia is a province with a diverse climate that varies depending on latitude, prevailing winds, topography and proximity to water. While it is situated midway between the equator and the north pole – a position further south than the fine grape growing regions of Germany, forexample – Nova Scotia is essentially at the climatic limit for grape production. Therefore, careful planning and management decisions should be made based on long-term weather and local site suitability information before a location can be assumed suitable for grape production.

Temperature related parameters, such as length and intensity of the growing season and extreme winter minimum temperatures are the main concerns for grape site selection in Nova Scotia. Additionally, the amount of rainfall and sunshine during the growing season will influence the success of a particular location.

The length of the growing season, defined as the period between the last spring frost and the first fall frost, is an important climatic parameter for selecting the quality of a site. This frost-free period must begin early enough so as to not damage the new, tender shoots and extend far enough into fall as to prevent injury to the fruit and the vines. In Nova Scotia, the frost-free period varies greatly from year to year and will be longest in coastal sites.

The intensity of the growing season is often measured by degree-day or heat unit accumulation which gives a good indication of the eventual maturity and quality of the fruit. Annual heat unit accumulation above 10oC is of interest for grape site selection because grape growth essentially begins at 10oC. The maximum average heat unit accumulation above 10oC in Nova Scotia is approximately 1000 in the better sites. Contrary to the frost-free period, degree-day accumulation will be reduced near the coast.

The magnitude, frequency and duration of winter minimum temperatures are an important consideration because of the risk of cold injury during the winter months. The risk of extreme minimum winter temperatures is reduced near bodies of water.

Microclimate differences may slightly alter the potential for success from one field to the next. Heat unit accumulation may be increased by establishing growth on south facing slopes compared to the cooler, low-lying areas. Windbreaks may help to prevent strong winds from damaging the grape vines and berries as well as increase the heat unit accumulation. On the other hand, they reduce the natural air drainage and may decrease the length of the frost-free period. As a weather sensitive investment, grape production requires sound judgment before and after planting. Thus understanding the climatic limitation of a potential site is a necessity.

Considering the three principal climatic factors together as shown in the following table, the best sites in Nova Scotia would be rated Fair Suitability.

Soil

If the climatic conditions are suitable for growing grapes then the individual should next consider the soil. Grapes can survive and produce on a wide range of soils. It is to the advantage of the grower, however, to select a soil which has good internal drainage and a potential rooting depth of 80 cm or more. These characteristics can be recognized in the field by examining the soil to a depth of 1 m. Well drained soils have brightly colored horizons, while imperfect and poorly drained soils have mottling (spots of orange or red material) or dull coloration in the top 50 cm.

Moderately well drained soils have mottling or dull coloration between 50 and 100 cm. A restricting layer can be determined while exposing the site. As the degree of difficulty to excavate the site increases the chances of root penetration decreases.

An additional feature to look for is a uniform sandy loam to loam texture. If a restricting layer is absent in the top 80 cm, these textures usually have an adequate water holding capacity for periods of low rainfall. Further information on soils is available from soil maps and reports. These can be obtained for most parts of the province from Agriculture and Agri-Food Canada (http://sis.agr.gc.ca/cansis/) or the Geomatics Centre, Service Nova Scotia and Municipal Relations (http://www.gov.ns.ca/snsmr/maps/).

Since the above soil conditions are limited in distribution, the potential grower may have to settle for less than optimum soil conditions. In Nova Scotia, this usually means less than adequate internal drainage, a restricted rooting depth or a combination of both. Developing these soils will require the installation of tile drainage to improve internal drainage and possibly subsoiling to increase potential rooting depth. Both improvements will be required before planting. In addition, subsoiling may be required after establishing the vineyard. Consult with suitable drainage engineering expertise for detailed recommendations. Also, because tiling and to a lesser extent subsoiling are expensive, the potential grower should carefully evaluate the potential yields and returns before proceeding with planting.

Vineyard – Site Selection

The success of a vineyard is closely linked to the location; therefore, a significant amount of time needs to be spent in the evaluation and selection of the site. When evaluating a site for growing grapes, it is important to consider the climate, topography and soil properties.

The climate in both summer and winter has a significant influence on grape vines. Grapes are very sensitive to extreme temperatures in the winter. It is the length of the growing season and the total heat unit accumulation that determines the varieties that will ripen on any given site. An average of 900 heat units is considered the minimum necessary to ripen the early vinifera varieties in Nova Scotia. There are many areas of Nova Scotia that meet this minimum requirement. It is also suggested by some that the timing of the heat units and the hours of sunshine are also of importance. The effective growing season for grapes is considered to be the time between the last spring frost (-2 C) and the first frost in the fall below -2 C. Most grape varieties require a minimum of 150 frost free days. The frost free period varies significantly over very short distances and is influenced significantly by topography. There is considerable variation in varieties tolerance to the minimum winter temperatures. Some sources indicate that the minimum temperature is -23 Celsius however vines have been known to survive -29 Celsius. The health of the vines plays a significant role in their ability to tolerate the cold in the winter.

It is preferred that a site for growing grapes has a south facing slope for air drainage and maximum interception of solar radiation, as well as shelter from strong winds. When considering soil as part of selection, it is important that the soil be well drained. A naturally well-drained soil is ideal, however in the case where drainage is not ideal and other site factors are favorable the soil drainage can be improved with the installation of tile drainage.