Northern Viticulture: Reviews and Studies

By Juha Karvonen

Plant breeding and global warming has made it possible to grow adapted grape varieties in higher latitudes, north of 52 N latitude in Europe. The northernmost grape growing occurs nowadays in the Nordic countries (Denmark, Sweden, Norway and Finland), the Baltic countries (Estonia, Latvia and Lithuania) and Poland. Some books available in English quite limited discuss the influence of climate, soil, photoperiodism, and long days during the growing season on grape growing in these new viticulture areas. This book does not provide direct hints on viticulture and does not act as a "cookbook" for wine growing, but instead explains how the current northern growth conditions differ from the growth conditions in the traditional viticulture countries, and what requirements they impose northern viticulture as well as how climate change will influence on them.

- First time I found so much climate information on one time specifically for the vine. The work that is done is a large volume and enriches the information on vine for Nordic countries. Assoc. prof. Ludmil Angelov, Head of Faculty of Viticulture and Horticulture, Agricultural University of Plovdiv, Bulgaria

• Language: English
• Publisher: Books on Demand
• Release date: Jan 18, 2017
• ISBN: 9789523308589

Juha Karvonen

Juha Karvonen on ammatiltaan lääkäri, joka eläkkeelle jäätyään opiskeli viinintuotantoa ja markkinointia Itävallassa. Hän suoritti Helsingin yliopistossa agronomin sekä matalous- ja metsätieden maisterin tutkinnon. Väitöskirjatutkimuksen aiheena oli viiniköynnöksen nykyiset ja lähitulevaisuuden viljelymahdollisuudet Etelä-Suomessa.

Book preview

To my grandfathers

Contents

Preface

Reviews

Short history of the northern grapevine

Requirements for viticulture in the north

Significance of snow and coverings

Comparison of the growing conditions of grapevines

Properties of northern vines and grapes

Climate change

Studies

Planting depth of grapevines in the Baltic Sea region

A thick layer of snow is a winegrower´s friend

The real effect of covers on vineyard subsoil temperature

The growth cycle of grapevines at 60°N latitude

Vitis cv. Zilga is a viable vine variety for the northern climate

Have climate changes altered the soil temperature regimes around the Gulf of Finland?

Phenolic compounds in northern grapes

Does climate change enable grapevine to grow in southernmost Finland?

Existing wine-growing conditions in northern Europe and impact of climate change on it

References

Subject Index

Preface

My idea to experiment with wine-growing at high latitudes in Northern Europe came to me while I was a visiting researcher at the University of McMaster in Ontario, Canada. Near the University, 40 kilometers north of Niagara Falls, were about 20 vineyards established by European immigrants which produced, in my opinion, quite good wine from Vitis vinifera L. varieties in circumstances corresponding to those of Southern Scandinavia.

At the end of my carrier, I began studying wine growing at Napa Valley College, in California and continued my viticulture studies at the University of Applied Sciences Eisenstadt, Austria. Later, I received my MSc (horticulture) from the University of Helsinki. On the basis of my studies and experiments I have also written following books in Finnish: Arktisen viininkasvatuksen oppaan (Guidebook to Arctic wine growing) and Viiniköynnöksen kasvatus Suomessa (Viticulture in Finland).

I have also written Northern viticulture based on my own 25 years of experiments and research on viticulture in the southern regions of Northern Europe and the Baltic Sea region at 55 – 60°N latitude. The book deals with the suitability of the current climate as well as circumstances and conditions of these regions for viticulture and how predicted change in the climate should facilitate it.

I express my deep gratitude for invaluable contribution to Mr Jaan Kivistik, at Räpina Aianduskool, Räpina, Estonia; Mr Lars Hagerman, at Domain Aalsgaard, Denmark; Mr Edgars Zihmanis, at Vīnogu Dārzs,Tervetes pagasts, Latvia; Mrs Lena Jörgensen and Mr Murat Sofrakis, at Vingården i Klagshamn, Klagshamn, Sweden, Mrs Helena Tiililä and Mr Raimo Saar, at Tiililä Farm, Pälkäne, Finland, meteorologist Asko Hutila, at Finnish Meteorological Institute, Helsinki, Finland, and secondary school lecturer Pekka Karvonen, Vehmersalmi, Finland.

I have received valuable technical assistance from Mr Mikko Niemi of Ekoweb in Turku, Finland, and from MSc Jyrki Ollikainen at the School of Information Sciences, University of Tampere, Finland, as well as invaluable scientific support from PhD Riitta Törrönen, University of Eastern Finland, Kuopio, Finland, and Prof. ing. Pavel Paulovšek, at Mendel University in Brno, Czech Republic.

Above all, I thank my wife Anna-Liisa for her assistance and everything else.

Juha Karvonen

Tampere, Finland, April 2016

Reviews

Short history of the northern grapevine

The history of the European grapevine (Vitis vinifera L.) originates in the Fertile Crescent along the Euphrates and Tigris rivers some 10,000 to 12,000 years ago. From there the vine has found its way, through Egypt and Greece, to the Mediterranean countries and, through the Roman Empire, to Central Europe. The Greeks used wine both a drink and a mercantile product, but the Romans used it for their expansion policy also. The present European borders of viticulture roughly follow the borders of the Roman Empire and Charlemagne's (768 – 814) empire.

Viticulture nearly vanished in Europe during the Migration Period. During Charlemagne's reign it recovered and retuned rapidly to its former regions. Charlemagne favoured viticulture and passed laws promoting it. At this time, Nordic inhabitants became more familiar with wine. Then they made lively fur trade with the Franks and Frisians. At that time, the Nordic countries dominated European fur trade, which tempted Central European immigrants northward. These immigrants brought with them knowledge of viticulture and wine making.

Wine had attracted northern people ever since they learned to know it through their trade, expeditions and military campaigns to the south and west. Wine made from grapes has always been an imports in Northern Europe. Vikings made honey wine, whose manufacturing method has survived until our time. The earliest findings related to grapes discovered in Southern Finland date back to the 4th century AD. These included grape seeds probably not from grapes grown in Finland, but from dried grapes sold by foreign merchants.

We have mainly the Romans to thank for Central European viticulture, which reached 51°N latitude (Cologne, Freyburg, Saale-Unsrut) in Continental Europe, and even 55°N latitude in Britain, the same latitude as Copenhagen. Thus far, 50°N latitude has been considered the northernmost boundary for viticulture, which, as a result of global warming, has begun to migrate towards the north and north-east.

The Baltic Sea region (54 – 57°N), south of the Baltic Sea, had viticulture during the warm medieval period of the 14th century (Gladstones, 2011). In the protection of European monasteries viticulture spread to Denmark in the 15th century, but the climate cooling during the Little Ice Age in the 16th century almost completely snuffed it out. Estimates (Stocker et al., 2013) indicted that the temperature of the northern hemisphere reached its lowest in the 16th century, when it was on average – 0.65°C lower than the annual mean temperature of 1881 – 1980.

A grave monument depicting wine transport in Augsburg (48°N; 10°E) from 200-230 AD.

Remnants of northern medieval vineyards are still visible in the Latvian town of Sabile, where viticulture began in the 15th century, survived through the cold period of the 16th century, and revived during the brief warming of the 1930s – so much so that the period even saw overproduction (Zihmanis, 2011, personal communication). However, Word War II and the communist regime ruined it almost entirely. In England, the vine was cultivated in the 11th and 13th centuries, but there, too, climate cooling and the Puritan regime put an end to it for centuries.

Medieval viticulture did not extend to Finland, Sweden and Norway, but greenhouses of the manors of southwest Finland and Southern Sweden in the18th century did grow vines imported from Central Europe and the Baltic countries. Grapes were used not for wine making, but simply to eat during parties. Greenhouse viticulture practiced by the gentry spread even to Northern Savonia province in the beginning of the 19th and 20th centuries (Ollikainen, 2010, personal communication). At the same time, the first experiments with wine growing on open land began in Southern Finland, where reports of vine pests soon followed (Reuter, 1914).

Professor Olavi Meurman began open land viticulture experiments in the 1920s and continued them into the 1950s. He also published several research papers and reviews. Meurman used North American Vitis riparia L. and Vitis labrusca L. varieties, both of which tolerated frost and returned a good yield in southwest Finland. However, due to their long ripening period they did not yield fruit on open land in central Finland.

The warming of the Nordic climate, which began more than a century ago, will continue further as a consequence of the greenhouse effect (IPCC, 2001; 2007; 2013) and likely shift the professional viticulture and wine making northward up to 60°N in 2041 – 2070. Denmark, Poland and Northern Germany would be the new wine production areas. Respectively, conditions for viticulture in Southern Europe (e.g. the southern parts of the Iberian Peninsula), will deteriorate owing to heat and decreasing precipitation (Fraga, 2014). Current wine production areas will see less frequent rainfalls, but in greater quantities at a time, which will lead to flooding.

Precautions should be taken by breeding plant species and varieties, which require less water and are more heat resistant. Excessive heat turns the red wine grapes pale and decreases their anthocyanin and flavonoid content. Furthermore, heat impairs the quality of red wines. All of this would change the temperature-based classification of current wine production areas or new cool regions would have their own classification (Santos et al., 2002; Fraga, 2014).

A vineyard in Sabile, Latvia, dating from the 16th century, uses terraced growing of a vine variety known in Latvia as autochtonous 'Zilga'.

At present, Central and Southern Europe vine varieties do not necessarily thrive in northern latitudes despite global warming. The Central and Western European varieties cultivated in the currently marginal growing conditions in Northern Europe seem to have the best prospects. Securing the production of high-quality wine will require the breeding of vine varieties resistant to plant diseases and pests and suitable for cultivation in the north in good time. They could give Nordic wine unique character, which differs from that of other more traditional European wines.

Requirements for viticulture in the north

Late and early frosts are problems for wine growers everywhere, and they determine the choice of vine varieties. Even though the end of April may be warm in the Baltic region, and vines typically begin to awaken from their dormancy and their first buds open, severe frosts (-5°C) can sometimes occur in the middle and in even towards the end of May. If the vines have begun to sprout new summer shoots, they are in danger of freezing, especially if they are uncovered. Even so, this is no reason to fret. Vines have reserve buds, which develop new shoots, once the weather has finally warmed up. However, this stresses the vines and delays flowering, so the vintage does not have time enough to ripen before the early frost. Similarly, delayed flowering also delays the dormancy of shoots, and winter resistance suffers.

Due to weather conditions and sudden temperature changes in spring, vine varieties suitable for northern conditions should not sprout and flower too early. Therefore, vine varieties suitable for 60°N latitude should not sprout before early-May, and flower before mid-June. Then the grapes will reach their normal size in August and begin to ripen in the first half of September. By late-September they will be ready for picking. Even in the southern parts of the Nordic countries the grapes of vine varieties should ripen within ten to twelve weeks after flowering.

The first autumn frosts in the Baltic Sea region occur at the end of September, but the growing season can last an additional month or so thereafter. This gives the vines time to strengthen and ripen before winter. If the vine varieties are traditional, slowly ripening varieties from Southern Europe, the leaves and shoots remain green with high water content and can freeze. If the bark color of the shoots has no reddish or brownish color changes, the vine is not ready for dormancy. Thus, the vine´s capacity for wintering weakens decisively, and the vine may suffer frostbite and damage during a strong winter.

The flowering of several European red wine vines is sensitive to late frost. The grapes of old Central and Southern European varieties ripen, from flowering to harvest, in approximately one hundred days (i.e., three and half months). That is why dark grapes, which flower early and ripen late, are cultivated mainly in Southern Europe. Owing to breeding and crossing, the boundary of red wine production has extended recently to the more northern regions.

Austria which belongs to the EU's northern viticulture zone A (Finland, Sweden, and Denmark belong to this same zone), has cultivated mainly white wine varieties. Nowadays, however, Austria grows more red wine than white wine varieties. Crossing frost-sensitive European Vitis vinifera L. varieties with the frost-resistant Asiatic Vitis amurensis Rupr.varieties and North American vine varieties has improved the frost and winter resistance of European vine varieties.

In the Northern German wine regions and in Hungary, the weather in spring finally warms up only about two or three weeks before it does in Southern Finland. In Germany night frost can occur even in the beginning of May, so, although the differences are rather small in spring, they become more apparent in autumn. The German and Hungarian autumn, where the daily temperatures may exceed 20 °C (though still with