Allotment holders are being warned to prepare for up to a week of unusually late frosts which threaten to kill off spring blooms, fruit in flower and emerging plants such as potatoes.
It could spell an end to what horticulturalists had been hailing as a vintage spring after the effects of the winter “big freeze” caused many plants to burst into flower simultaneously.
Experts also warned allotment enthusiasts to delay planting out tomatoes and other delicate fruit and vegetables, which would normally be safe to plant out in May, this year.
With overnight temperatures set to fall as low as 26F (-3C) in some parts of Scotland over the next few days, even milder areas in the south are being warned to prepare for over overnight lows close to freezing.
Daytime temperatures will also be unseasonably cold, with highs of between 50F (10C) and 59F (15C) expected, and the wintry conditions could last into next week, the Met Office warned.
Alan Power head gardener at the National Trust’s Stourhead gardens in Wiltshire said that it was the latest warning of widespread frost in recent memory.
“It is a worry,” he said. “Usually you can relax once April has gone out, a lot of people will have prepared pots and hanging baskets, you just don't expect to have to protect them.”
With spring arriving up to four weeks later than usual this year because of the cold winter, visitors to the gardens have been treated to the rare sight of camellias, magnolias and rhododendrons all in flower at once.
But he warned: “It will definitely shorten it, mother nature is going to steal back again the four weeks we had stolen from her.”
Andy Bodenham, a Met Office forecaster, said: “We are going to see temperatures down to just a few degrees above freezing in many areas, and certainly cold enough to warrant protecting delicate plants.”
Allotment holders should seriously consider protecting emerging potato stems, if large then a fleece covering would be useful, but if it is possible to heap more soil over the stems and foliage then that is a simpler protection.