Giant dahlias bloom in unseasonal warmth
5 December 2011
Giant tree dahlias - Dahlia imperialis - have been flowering, in some cases for the first time in many years, following the UK's second-warmest autumn on record.
D. imperialis, which can reach 5m (15ft) or more, is grown mainly for its imposing stature and spectacular foliage in this country, as it is usually cut down by frosts well before it gets mature enough to bloom.
But with the first frosts in many parts of the country a month or more later than usual, several specimens have reached flowering size and produced copious amounts of delicate, downward-facing lilac flowers.
At Berkeley Castle in Gloucestershire, which enjoys a microclimate by virtue of its position by the River Severn, a 10-year-old specimen growing against a south-facing stone castle wall reached 6m (20ft) tall and was still flowering profusely at the beginning of December, producing over 100 flowers and thousands of buds.
Elsewhere, D. imperialis has flowered for the first time in eight years at Bicton College in Devon, and others have been reported blooming at the Lost Gardens of Heligan in Cornwall and Great Dixter in East Sussex.
The phenomenon is one of many unusual plant behaviours observed in the unseasonally warm temperatures: RHS Principal Horticultural Advisor Leigh Hunt has had reports of magnolias in flower during autumn and apple trees producing a second flush of blossom.
'Plants have had two months of extra growing time and they've taken full advantage of that to try and make extra seeds,' he says. '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.'