Plant-growing season in UK now a month longer than in 1990

The growing season for plants has become a month longer than it was a few decades ago, Met Office figures show. In the last 10 years, the growing season, measured according to the central England temperature daily record, which stretches back hundreds of years, has been on average 29 days longer than in the period 1961-1990, the data show. And while more of the year is warm enough for plants to grow, there has also been a decline in the number of frosty days in recent decades, the Met Office said.

Between 2006 and 2015, the plant growing season, which begins and ends with periods of consecutive days where daily temperatures average more than 5C (41F) and is without any five-day spells of temperatures below 5C, averaged 280 days.

Figures also reveal that six of the 10 longest growing seasons have occurred in the last 30 years, with 2014 topping the list at 336 days, or about 11 months of the year, while 2015 was 10th, with 303 days – about 10 months.

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Only three of the 10 shortest growing seasons have taken place in the last century – in 1979, 1941 and 1922 – while the years with the shortest season were in 1782 and 1859, at just 181 days.

Mark McCarthy, manager of the Met Office’s national climate information centre, said: “Between 1861 and 1890, the average growing season by this measure was 244 days, and measuring the same period a century later, the average growing season had extended by just over a week. For the most recent 10 years, between 2006 and 2015, the average growing season has been 29 days longer at 280 days, when compared with the period between 1961 and 1990.”

Days gripped by air frost, when the daily minimum temperature dips below 0C, also declined, with just seven years since 1990 when the number of frost days exceeded the 1961-1990 average. The frostier-than-average years include 2010, when the bitter winter had the most days of frost since 1917.

McCarthy added: “Although we have fewer air frost days on average than we experienced a few decades ago, the numbers can still fluctuate from year to year. Many people will remember vividly the cold spells during 2010 and 2013. In contrast, 2014 recorded very few days of air frost and was the lowest in the UK series from 1961.”