Earliest Recorded Blossoming of Grapevines in Germany
May 28, 2007
The extraordinarily warm weather in spring 2007 led to a rapid development of the vines
and an extremely early blossoming. According to Ernst Büscher of the German Wine Institute,
Mainz, the first vines in Germany, have blossomed about a week earlier than ever before. The
earliest recorded blossoming to date was in the Rheingau on June 2, 1993. On average,
blossoming takes place in mid-June.
Blossoming – A “Quiet Happening” Decisively Influences a Vintage
Actually, the flower clusters of grapevines are rather inconspicuous. Botanically, the
clusters are panicles – loose, irregularly branched flower clusters – with individual
flowers, or blossoms, on the end of each branch. If successfully fertilized, these blossoms
ultimately develop into grapes. Grapevines are “practical” in that many have the ability to
self-pollinate, and thus are not reliant on outside help from insects or animals. The overall
number of clusters provides an early prognosis in terms of potential yield – with emphasis on
“early.” Much can happen between blossoming and harvest, in terms of pests and disease, to
totally change this first outlook.
Büscher adds, “The next few days are extremely important. Temperatures should not fall below 59 F.”
Furthermore, cool, rainy weather hampers the optimal fertilization and immature berries
dry up and fall off the vines in a phenomenon known as “coulure” or “shatter.” Deficient
fruit set naturally reduces potential yield.
It’s understandable that vintners follow the flowering period quite closely, and in some
villages, there are “blossoming festivals.” From the end of blossoming, it is about 95 days
until harvest. The “baby” berries continue to develop from late June until early July and
begin to ripen in mid-August. Actual development depends on grape variety, as well as
weather conditions and microclimate within a site. Blossoming is the “birthday” of the new
grapes, and thus the start of 2007 vintage.
Background Information
The Grapevine – Botanical Overview
Originally, grapevines grew in forests and climbed up trees, as “creepers,” members of the
high-climbing woody vines known as liana. The earliest findings of grape seeds stem from the
early Tertiary Period (ca. 80 million years ago). Wild grapes of the species vitis silvestris
and vitis caucasica still thrive in the Upper Rhine, Switzerland and Balkans. Today’s wines
stem from the species vitis vinifera that are the result of specific breeding, accidental
crossings and natural mutations. About 8,000 different varieties are known. Grapes grow in
the Northern Hemisphere between the 30th and 51st degree of latitude and between the 30th and
40th degree of latitude in the Southern Hemisphere.
Ideal Temperatures
Average annual temperatures of more than 9 C (48 F), winter temperatures not lower than minus
20 C (–4 F) to avoid frost danger.
Blossoming Stage
Vines have flower clusters, each with several individual blossoms that form a closed “cap.”
The cap falls off during blossoming, the individual flowers appear, and glands in the vine
lend a fine aroma to the air. The measuring of the blossoming period begins when about 25%
of the flower clusters have blossomed (i.e. caps have fallen off) and ends when about 90% of
the caps have fallen off. In all, this phase can last from five to ten days, depending on
weather circumstances.
ABOUT WINES OF GERMANY
Wines of Germany, formerly known as the German Wine Information Bureau, is the exclusive U.S.
office of the Deutsches Weininstitut. Wines of Germany is focused on creating greater
awareness to further enhance the image and increase sales of German wine in the U.S. through
educational and promotional activities. It is the primary information source on German wines
for members of the wine trade, the media, and U.S. consumers. The promotional and educational
efforts of Wines of Germany focus primarily on Riesling, the most famous German grape
variety.
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