Key message
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The length of the annual growing season is increasing almost everywhere in Europe, mostly in Eastern and Northern part, and less in Western Europe, the Mediterranean and in southern Europe. In Slovenia, the length of the annual growing season is increasing, especially since the mid-1990s. According to projections, the duration of the annual growing season throughout Europe will increase in the future. This will affect the expansion of more thermally demanding plants to areas towards the north of Europe, where the cultivation of such plants has not been possible so far, and in the southern part of Europe where changed thermal conditions will allow the growing season to extend towards the winter season.  Mostly, in all parts of Central and South-Eastern Europe, dry and hot summers will hamper crop production.

 


The length of the annual growing season is the period between the day when the average daily air temperature in spring exceeds 5°C and the day when it drops below this value in autumn.

An air temperature of 5°C is generally recognised to be the lowest temperature threshold for plant vegetation. The 5°C temperature threshold is also used as one of the conditions for the classification of agro-ecological zones. In the context of climate change, it enables assessing the impact of changing climate on the development of plants and their environment. This indicator also serves as a tool in preparing for adaptation to new conditions, thus minimising the potential negative impacts of climate change.


Charts

Figure PP06-1: Average length of annual growing age within individual places, Slovenia, reference periods 1961-1990 and 1991-2018
Sources:

Meteorological data archive, Slovenian Environment Agency, 2019

Show data
1961-1990[number of days] 1991-2018[number of days]
Ljubljana 243 258
Novo mesto 238 252
Bilje 278 282
Slap pri Vipavi 276 286
Murska Sobota 237 246
Maribor 243 250
Rateče 187 203
Figure PP06-2: Changes of length of annual growing age in Ljubljana, 1961-2018
Sources:

Meteorological data archive, Slovenian Environment Agency, 2019

Show data
growing season[number of days] 5-y running average[number of days]
1961 279
1962 227
1963 249 250.80
1964 256 240.20
1965 243 248.40
1966 226 247.20
1967 268 243
1968 243 241.20
1969 235 245.40
1970 234 245.80
1971 247 240.40
1972 270 238.60
1973 216 244.80
1974 226 243.20
1975 265 244.80
1976 239 252.60
1977 278 256.60
1978 255 248
1979 246 249.40
1980 222 238.20
1981 246 234.60
1982 222 232.40
1983 237 230
1984 235 229.40
1985 210 229.80
1986 243 228
1987 224 231.40
1988 228 241.40
1989 252 240.20
1990 260 252.20
1991 237 251
1992 284 255.60
1993 222 249.80
1994 275 251.60
1995 231 244.60
1996 246 246.20
1997 249 243.40
1998 230 254
1999 261 254
2000 284 260.20
2001 246 261.60
2002 280 263.20
2003 237 256.20
2004 269 261.60
2005 249 258.80
2006 273 259.20
2007 266 262.40
2008 239 263.20
2009 285 258
2010 253 260
2011 247 259
2012 276 264
2013 235 267
2014 310 268
2015 265 268
2016 256 258
2017 272
2018 236
Figure PP06-3: Timeline of change for the length, beginning and end of growing season in Ljubljana over the 21st century
Sources:
Note:

The timeline of change is shown for temperature threshold 5 °C for two scenarios relative to the reference period 1981-2010. Bold coloured curves show smoothed model median and lighter colours show model spread. Under RCP4.5 the growing season length will increase by approximately 25 days and under RCP8.5 by approximately 60 days. 

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Figure PP06-4: The rate of change in the growing season length , Europe, 1985-2014
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Goals

• To estimate the effect of climate change on plant development.
• To prepare adaptation procedures for the newly arising climatic conditions and mitigation of possible adverse effects.


Methodology

Date of data source summarization

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