Dahlias Imperialis can reach up to 15ft or more tall and usually does not flower during winter. For this reason, many grow the plant for its great stature and foliage.
One specimen at Berkley Castle in Gloucestershire reached 20ft tall and has produced thousands of buds and over a hundred flowers. The plant is continuing to flower even though it is December.
Several other specimens have also been spotted blooming in areas such as Devon, Cornwall and Essex.
RHS Principal Horticultural Advisor Leigh Hunt discussed the unusual behaviour of plant species when warmer temperatures occur during autumn or winter. He has received reports of other plants, such as apple trees and magnolias, blooming during autumn.
“Plants have had two months of extra growing time and they’ve taken full advantage of that to try and make extra seeds,” he said.
“It’s unlikely they’ll succeed, but it’s as though they’re taking a punt – from their point of view, it’s worth a go