The Woodland Trust has only received 31 reports of ripe blackberries so far to its Nature’s Calendar survey, in which members of the public record the signs of the changing seasons.
By August 1 last year, there had been “first ripe fruits” spotted at more than 300 locations across the country as far north as Yorkshire and Newcastle.
Those blackberry records fitted a recent trend in which autumn fruiting has gradually taken place earlier, but this year the cold spring seems to have held back the leafing and flowering of species - with a knock-on result for ripening fruit.
UK temperatures in March were 0.2C (0.4F) below average and in April they were almost one degree (0.9C or 1.6F) below the average for the month. Only at the end of spring did they rise above average, the Woodland Trust said.
Dr Kate Lewthwaite, Woodland Trust citizen science manager, said: “While there’s no need to pack away the cooking equipment, people may have to wait a little longer for a blackberry harvest.
“Our records actually show a long-term trend for autumn fruiting to be occurring earlier and earlier, with wildlife having to adapt accordingly to find sources of food.”
Last year the average date for ripe blackberries being recorded throughout the country was August 11.
The Woodland Trust is asking anyone who spots a ripe blackberry to record when and where they see it, to help track autumn’s progress across the UK.
To record “first ripe fruits”, people need to look at a bunch of blackberries and note when the first fruit of the cluster ripens.
Nature’s Calendar is a continuation of seasonal records dating back to the 18th century, when it was first started by Norfolk landowner Robert Marsham. Now tens of thousands of records are added each year by the public.