Professional gardeners are continuing to see flowers blooming much earlier than usual, with camellias at a number of gardens already showing good displays.
Some gardens are concerned that the best displays will be over before visitors start coming to the sites. Borde Hill Garden in West Sussex is seeing camellias blooming that normally flower in March/April.
"All through the autumn and winter we've had things flowering out of time and at the moment the camellias are doing quite well - too well really," said head gardener Andy Stevens.
"They are about five-to-six weeks ahead. We don't reopen until 10 March, so the ones flowering now will be long gone. There are still a few left to flower so I don't think we'll be completely without but the display won't be as good as last year. We're hoping for a bit of a cold snap to hold them back."
Camellias are also flowering in the conservatory at Chiswick House in west London, which is holding a Camellia Festival on 18 February to 18 March. But a representative said it was likely that there would still be a good display.
Kew Gardens head of phenology Sandra Bell said a number of the 100 plants monitored were flowering early. For example, Scilla mischtschenkoana normally flowers in February but came into bloom on 29 December.
"There are some daffodils that are early," she added. "Narcissus pseudonarcissus came out on 11 January, which is very, very early. The average date for it to start flowering in the new millennium is 27 January. That date is 16 days earlier than the average for the 1980s, so they are very early this year. That earliness is at the front of a trend.
"The data would seem to demonstrate that there has been a trend towards earlier flowering in the spring since the 1980s."
View From the Nursery - High-quality blooms ahead of frosts
The Sir Harold Hillier Gardens near Romsey has 100 different camellia varieties in flower, according to camellia grower Jennifer Trehane, owner of Trehane Nursery.
"Trehane also has a large number and there is a very high quality of bloom - until the frost comes. We just had a frost of -4 degsC and now the second lot of blooms are coming out. There are some varieties that flower over eight, 10 or even 12 weeks, with flush after flush of blooms.
"The problems come with prolonged frost and camellias in containers, when the frost can cause root damage. We don't know what's in store before the winter is over, but people are still buying camellias and the nursery is very busy at the moment."