Many plants have continued to bloom this autumn due to the unusually mild weather and wet conditions.
The unseasonal plant growth comes as the UK recorded 10 months of unprecedented above-average temperatures.
Gardeners have said the apparent “second spring” has led to fuchsia and dahlias blooming in October, while others report their strawberry trees producing double the amount of fruit.
John David, the head of horticultural taxonomy at the Royal Horticultural Society, told the Guardian: “Recent mild conditions and plentiful rain will have encouraged unseasonal plant growth.
“This summer caused quite a few plants, shrubs and trees to lose leaves or die down to survive the heat and drought. It was noticeable that when the rain returned in September, quite a few plants produced new leaves that would not normally do so at this time of year, and some also came into flower again.”
He said the autumn had been “exceptionally mild” so far and predicted the unseasonable weather would continue.
Powis Castle and Garden, near Welshpool in Powys, said its strawberry tree had produced double the amount of fruit this year - the first time the gardening team had witnessed such an increase.
Ned Lomax, head gardener of Bodnant Garden in Conwy, said: "Some plants are actively growing or flowering now as a response to the mild and wet weather following the long, dry summer when growth wasn’t possible."
It comes after the UK experienced an "unprecedented" heatwave this summer, which saw temperatures top 40C for the first time.
Wildlife experts said the extreme weather recorded this summer will significantly increase pressure on vulnerable species and has already had a devastating impact on some ecosystems, particularly where freshwater habitats have dried up.