An exceptional Terroir

The farm where the Vineyard Domaine des Cotes d’Ardoise is now established existed since the end of last century.

According to the people who spent their childhood in this farm, in the 40s, the farm was already renowned for producing the first vegetables of the entire region in spring as well as the last ones during fall because the freezes occurred earlier in spring and later in fall than anywhere else. This means that even at that time, the microclimate of Cotes d’Ardoise was already known. This peculiar climate was again noticed by Mr. Christian Barthomeuf who bought the farm in 1977 and had the idea to start the vineyard.

The Vineyard Domaine des Cotes d’Ardoise is located 80km south of Montreal, near the Quebec-Vermont border in the Municipality of Dunham, Brome-Missisquoi County on a land spanning on 175 acres, where 115 are forest-covered.

Geographical and Climatic Conditions of the Vineyard

The Vineyard Domaine des Cotes d’Ardoise is established on the Appalachian foothills that dominate the very large plain of the St. Lawrence River at an altitude of 150 meters. It is a terrain of ungrafted soil derived of slate and argillaceous shale formed after a landslip in the Primary Period that was heavily eroded after the Secondary and Tertiary.

This quantity of slate, shale and other different rocks that form a very superficial layer of ground (less than 30 cm in certain places) makes it possible to retain maximum heat after the hot season and to noticeably increase the temperatures during summer and at night. Three important facts add up to this.

  • The plots of land located on a gentle slope (negative characteristic at the time of July’s big storms) are surrounded by a strong hedge of trees at the four cardinal points; therefore, they are protected from the wind.
  • The land is already located in the warmest and least rainy region of Quebec (influence of the Missisquoi bay.)
  • Above all, the Cote d'ardoise Estate is amply bathed by a layer of a warm air, acting as a buffer, over the St. Lawrence valley. Indeed, over every valley there is a layer of warm air whose thickness and altitude vary depending on the valley.

For the St. Lawrence valley, this layer of heat is located between 450 and 750 ft high. The lowest part of the vineyard, corresponding to the road, is precisely located at 450 ft above sea level.

It is to note that the vineyard is located on the first hillock encountered when traveling from Montreal. In clear days it is possible to see Montreal when placed in the vineyard’s highest grounds. This layer of warm air makes an important difference regarding the duration of the growing season, i.e., the non-freezing period.

The last freezes of spring and the first ones of fall usually occur on clear-sky windless nights. Warm air, being lighter, will rise; while the heavier cold air will come down. The cold air descends along the slopes to stop and remain at the foot of the hills, otherwise called, the lowland. Recall the weather forecast that is frequently heard during spring and fall « FREEZING RISK TOMORROW NIGHT ON THE LOWLAND ».

The layer of warmth and the sloped terrain allow for this vineyard to have 2 to 3 frostless weeks more during spring and fall than the adjacent terrains located just a few hundred meters away. This is the reason why it is possible to grow certain grape varieties, red among them, which require a longer season in order to reach ripeness.

Exceptional Climate at Vineyard Domaine des Cotes d’Ardoise

According to the statistics of the meteorological stations, the Dunham region has an average of 144 days without frost per year. However, at the vineyard, we have a yearly average of 182 days, calculated between 1981 and 1988.

During that period, the number of non-freezing days changed from 157 in 1986 to 195 days in 1987.

Days without frost at the vineyard
Year Period Days without frost
1988 April 19 to October 30 194
1987 April 20 to November 2 195
1986 May 2 to October 9 157
1985 April 20 to October 28 192
1984 April 27 to October 5 165
1983 April 18 to October 21 185
1982 April 16 to October 9 190
1981 April 23 to October 12 180

Contrary to what one could think, the region of Dunham enjoys the same number of crop heat units as the Niagara peninsula in Ontario. Crop heat units are calculated according to temperature and sun exposition duration. However, these units are distributed differently here than in the Niagara region.

The Niagara Peninsula is influenced climatically by the Ontario and Erie Lakes. This makes the temperatures of the beginning of the summer much cooler (especially at night, since water heats up slower than land.) Consequently, plant growth starts later in Niagara than here.

Therefore, our grapevines bloom 10 to 15 day earlier. On the other hand, the opposite effect takes place during fall and starting as of mid-September, the Ontarian nights are milder and the risk of sudden freezes is almost none.

The statistics provided by different federal and provincial research stations have confirmed that, for example, for the years 81 and 82 the quantity of crop heat units registered at the Vineyard for the months of May, June, July, August and September was larger than at the Niagara Valley and considerably larger than at certain neighboring regions like Farnham and Rougemont.

Crop Heat Units
Region Year 1981 Year 1982
Frelighsburg 1813.25 1777.00
Farnham 1875.25 1772.00
Franklin 2052.25 1899.25
Rougemont 1849.50 1910.75
Vineland Ont. 2244.00 2015.00
Cotes d'Ardoise 2250.00 2020.50

What really differentiates the Niagara Region from ours is the winter, which is much colder here.

In fact, during winter and according to the variety, hybrid or V. vinifera, the buds can be destroyed at -15 or -25 C if the necessary precautions are not taken. Due to this, the buds of the majority of the vines grown at this moment need to be protected during winter to ensure that they will bear fruit on the next summer season.

One method of doing this is to cover the base of the plant, including the lower buds, with a mound of soil approximately 30 cm high. This is called “hilling up,” a technique used since long time ago in China, and like the wheel, it seems to have been reinvented several times from then on. It is for this reason that since 1980, the crop is planted leaving 2 meters between the rows of vines allowing us to gather the soil in the middle of the row and place it around the vines.

The rows are wider here than anywhere else in Europe, Australia or California. Therefore; the vine density per hectare is lower and consequently the production per hectare is less.

The hilling-up takes place during November. We need to watch out for early sudden freezes and not be taken by surprise. This is the reason why the pruning needs to be done in a way that the next year’s buds will be located in a low position and that they can be protected by the hilling-up. We are obliged to make “low height crops.” We will never be able to harvest the grapes at man-height for certain varieties that we grow currently.

Some recently developed varieties are more resistant to cold and without a doubt, in the years to come; other varieties with special characteristics for cold weather like ours will make their appearance, unless, it is our climate that will change instead due to global warming.



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879, rue Bruce, route 202
Dunham (QC) J0E 1M0

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