To help visualize the climate data, we produce the three graphs cycling above these tabs (click on the small circles to freeze one). The first graph shows the cumulative GDD(Growing Degree Days, a measure of accumulated heat during the month); the second shows both the monthly rainfall and GDD, and the third shows daily rainfall and temperatures for the growing season of April to Oct 2019
Cumulative GDD Jan to Oct 2019
Cumulative GDD are higher than in all but 3 of the previous 10 year in all areas, so really it’s been another in our string of warm summers. September rains, however, have led to earlier harvests for many of us.
Monthly GDD and Rainfall Jan to June 2019
Compared to recent years, September Growing Degree Days (GDD) were slightly under average in Saanich & Cowichan, slightly above average in Comox, and a bit higher than last Sept. in all three areas. Rainfall, which is much more variable than GDD, was above average in all areas, but it was not the wettest September of the past dozen years. September 2019 had similar rainfall to Sept. 2018 in Saanich and Cowichan, but Comox had only half as much rain in Sept. 2019 as compared to last year.
Daily Highs and Rainfall September 2019
The beginning of the month was warm and dry, but summer came to an abrupt halt around Sept. 12 with a significant rainfall in all areas, particularly Cowichan (33 mm on the 12th). From that point until Sept. 27 there were almost no rain-free days, leading to increased botrytis risk, especially for varietals prone to splitting such as Ortega. Sept. 2019 was rather wet in the Okanagan too; Kelowna had 12 straight days with at least some rain starting on the 7th and was well above average for the month.
Long Range Forecast
The 3-month forecast, not that it matters much for growing grapes, is rather neutral – no unusually warm or cool temperatures expected, and no La Nina or El Nino.
For grape growing, the most important physical property of soil is its texture, which refers to the particle sizes in the soil. Soil texture influences water holding capacity, root growth, overall vine vigour, soil fertility, and aeration. Soil particles are divided into 3 classes: sands (coarsest), silts and clays (finest). Ideal textures for vines are loams (roughly 40% sand, 40% silt, and 20% clay). Other important soil characteristics are structure (content of stone fragments, hardpan layers, etc), pH (acidity), and nutrient content. Vines often need deep roots, so hardpan layers need to be broken up with deep ripping. Soil pH should be 6.0 to 6.8 for optimal uptake of nutrients. Organic matter should be modest, 2% to 3%, to avoid too much vegetal growth.
Grape vines don’t like wet feet, so also important is good drainage, a factor of both texture and slope.
Saanich has had a complex geological history since the last ice age, and therefore has a wide variety of soil materials: glacial till soils of mixed textures, beach/alluvial soils of medium to coarse textures, and marine clay soils of medium to fine textures. Saanich soil pH is often too low (too acidic) and needs to be raised by adding lime for several years.
Symphony’s vineyard site on Oldfield Rd consists primarily of a rocky glacial till loam. Our steady slope provides excellent drainage, which allows the soil to dry out and warm up relatively quickly during the summer. We deep-ripped before planting to break up occasional clay layers, and added lime for several years to adjust the soil pH. Every couple of years we have the soil analyzed to help plan our fertilizer program. We maintain a custom-mix grass cover crop between the rows to reduce soil erosion and compaction, improve the soil structure with organic matter, and promote soil flora and fauna.
Wine grapes grow primarily in areas where the mean annual temperature varies between 10°C and 20°C, shown on the map below. Colder than this, grapes won’t ripen or suffer too much winter damage; warmer than this, they won’t go properly dormant during winter and therefore won’t bear fruit the following summer.
As you can see, BC wineries are near the edge of the northern viticulture zone. Our own growing area is located near the ocean, which of course strongly moderates both our summer and winter temperatures relative to further-inland continental wine areas like the Okanagan. We also have a radically different rainfall pattern than the Okanagan – they have very little precipitation during the winter and start the growing year with very dry soils, while our wet winters mean we start with completely saturated soils.
Other important climate variables for successful winegrape growing are the amount of summer rainfall, the frost risk at each end of the growing season (April to October), and especially, the accumulated heat during the growing season, usually measured in Growing Degree Days (GDD). To obtain GDD, the average temperature above 10°C is calculated each day and cumulatively added up during the growing season, as illustrated below for two consecutive days which sum up to 9 GDD:
Growing Degree Days allow us to compare one year to others in our area, and to compare ourselves to other winegrape growing areas. Familiarity with the GDD concept will help you understand our monthly updates under the Saanich Climate tab.
Different winegrape varietals require different amounts of heat (GDD) to ripen, and it’s very important to plant grape varietals which are matched to your climate. A quickly ripening varietal planted in a hot climate will ripen during the hot summer, which is too soon – many of the wonderful complex aromas and flavours in wine develop during the fall, when the nights are cool and the leaves are beginning to turn. Conversely, a slowly ripening varietal in a cool climate won’t ripen at all.
Saanich is definitely a cool-climate viticulture region, and requires early ripening varietals. Our climate is perfect for crisp, aromatic whites such as Symphony’s Gewürztraminer, Pinot Gris, and Ortega; although our summers are relatively cool, there’s very little frost risk in the fall and we can leave the grapes hanging long enough to build up wonderful varietal flavours and aromas. Relatively few of the famous red grapes will fully ripen here; in a good year Pinot Noir can produce wonderful Burgundy-style reds, while in cooler years the same grapes can be used for lovely crisp dry Rosés or even whites like Symphony’s Blanc de Noir. At Symphony’s Oldfield Road and Starling Lane vineyards we have Maréchel Foch and Léon Millot, two French-American hybrids created in Colmar, Alsace in the early 1900’s (see our Grapes tab). Due to their partial parentage in quickly-developing American cultivars, Foch and Millot reliably ripen every year in our climate, and produce rich, fruit-forward medium bodied red wines.
Global warming will slowly increase the average heat in our growing seasons. In the medium term, however, the primary climatic factors we have to deal with are large GDD variation from year to year, and large yield variations tied to spring-time temperatures. Our growing season GDD often vary by 15% to 20% from one year to the next, which really drives home the point of planting suitable varietals which ripen regardless of the type of summer we’ve had. Grape harvest yields vary even more, from low crop years like 2012, to record harvests like 2014 in which all six of our varietals yielded 2 to 3 times the amounts in 2012!! The yield is not primarily connected to summertime heat, but rather to the springtime from bud-break (when cluster size is being set) to bloom (when fruit set occurs), and even to springtime of the previous year when the number of clusters for the present year is set. When conditions are perfect for all of these very temperature-sensitive processes, an amazing harvest results, as in 2014.