The lack of rain through August has already caused gardeners to lose flowers early.
Now the leaves are turning faster than usual and some trees are even dying for lack of rain.
Nigel Taylor, Curator of the Royal Botanic Gardens at Kew, said the famous gardens have already lost two trees and the situation would be “serious” for gardeners if rain does not come soon.
The Met Office said that while parts of Scotland, Northern Ireland and Cumbria experienced twice the normal levels of rainfall during August, parts of East Anglia had half the average amount. In the South East as a whole there was just 35mm of rain, compared to an average of 50mm. In September there has only been 13mm in the area so far.
The Environment Agency said the drier than average August, together with high temperatures at times, caused soil moisture deficits that particularly affects plants. The regional average is now 125.4mm, compared to an average shortfall of 86mm.
Mr Taylor explained that trees will shed their leaves because of a lack of water as well as the cooling temperature. The garden has lost two pine trees. Limes, horse chesnut trees and shrubs like hydrangeas are also suffering.
“We definitely have a drought here and autumn is coming early because of a lack of water,” he said. ” I do hope we get rain soon because it is quite serious.”
Mr Taylor said that autumn crocuses, meadow saffrons and cyclamen are doing well but other flowers like Michaelmas daisy and herbaceous perennials were suffering because of a lack of water and the heat.
He said temperature rise for the last few years has caused autumn to be warmer and wetter than usual, but this year it could be a very short gardening season if there is a cold snap as the withered plants will die off quickly.
“Normally autumn has been dragging into winter but this year it could be very short-lived,” he said.
Anglian Water admitted a lack of rainfall is affecting gardeners and farmers but it is not serious enough to bring in a hosepipe ban or affect water resources.