When Is the Beginning of Spring?

Many people will say that the calendrical beginning of spring is today, March 20. This is the day of the vernal equinox when the sun shines directly on the equator, and the length of day and night is nearly equal.

Well, there are actually two official dates for the beginning of spring. The meteorological date is always March 1.

I recently read an article in Die Zeit referring to a local date for the start of spring in Hamburg. This brought back memories.

 

La Treille today (©Loris von Siebenthal)

When I resided in Geneva, spring was officially announced when the marronnier de La Treille showed its first bud. The Grand Conseil de la République et canton de Genève explains how this came about on the Internet. Here is a translation of the essential details:

La Treille then (©Bibliothèque de Genève)

In 1720-21, two rows of chestnut trees (marronniers) were planted on the old fortifications in La Treille, a quarter of the old town. The climate of the time was harsh; Europe was going through the Little Ice Age, which lasted until the middle of the 19th century.

Poor Genevans in the 1800s! They suffered terrible cold weather in addition to the French occupation, which ended with severe winter as the Cossack winter. The worst was still to come in 1816 with a summer without the sun; the sky remained darkened by the dust of the colossal explosion of the Tambora volcano in Indonesia, which was unknown at the time.

In poorly heated houses, long and dark nights, watching the chestnut tree with its first leaf announcing spring - some must have feared that it would not return - brought the hope of beautiful days.

©Loris von Siebenthal

The first official observation of marronnier budding was noted in 1818, and those observations became a tradition.

©Bibliothèque de Genève

Note the climate change in Geneva. Over the years, the "local" spring date changed from the beginning of April to the beginning of March.


Back to Hamburg. When in this port city, a forsythia shrub near the traditional Lombardsbrücke* is in bloom, then there is officially the beginning of spring.

*Spanning the water link between the two lakes formed by Außen- and Binnenalster

Forsythia is an indicator plant blooming when there is no more frost. The soil has to be warm at seven degrees centigrade, even at night, because the roots won't absorb any water before then. So the most accurate determination of the beginning of spring is phenology based on the flowering, for the plants feel what man cannot determine.

©Die Zeit

Die Zeit continues, "The man reporting the beginning of spring is Jens Iska-Holtz; he is 81 years old. He has been coming here for 37 winters, every day in January, February, and March, to his forsythia, a family of oil-leaf plants, two meters wide, three meters high. This story can only be told as that of the two of them. Without the old man, the shrub is nothing, and the old man is nothing without his shrub. "

Jens is one of 1100 phenological observers in the land reporting to the head office of the German Weather Service located in Offenbach near Frankfurt. Most of them look at and serve as messengers for whole regions; Jens only looks at his shrub.

Red Baron has a personal phenology spring indicator looking out of his kitchen window. Every year a splendid magnolia tree starts to blossom from the end of February to the beginning of March. This year it is unusually cold for the season – we were spoiled by climate change in recent years – the first buds became visible on the ides of March. Spring has finally arrived in Freiburg!

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