Nowadays, the growing season starts more than 3 weeks earlier than round about 1900 and ends about 1.5 weeks later. This appears from figures published by the Dutch meteorological institute KNMI.
The growing season roughly starts when the temperature over the day and the night averages above 5 degrees and does not fall below that temperature until 1 July. The growing season ends in autumn when temperatures fall below 5 degrees again.
