Confused plants are flowering again due to the unseasonably warm weather, according to experts.
The Royal Horticultural Society (RHS) said strawberries and rhododendrons were among the plants seen blooming at its flagship garden in Surrey when they were not expected to flower again until next spring.
Temperatures have been hitting the high 20sC all over the country this week.
RHS chief horticultural adviser Guy Barter said the warm weather was causing a lot of late flowering.
At RHS Garden Wisley, rhododendrons, azaleas and spring flowering magnolias were blooming again. There were also signs of flowering fruit such as strawberries, apples and summer flowering raspberries.
Mr Barter said the growing season was getting longer because of climate change.
He added: "As a result, plant growth happens over an extended period which can see some types bloom again.
"After a long and good growing season plants are flush with resources and use these for a second flowering to produce a second crop of seeds."
Mr Barter said late summer warmth and light gave plants a chance to get ready for winter, with wood and buds ripening fully and becoming more resistant to cold damage.
The cooler, wet conditions of the summer had led to diseases such as downy mildews and potato blight, but these had largely dried up due to the higher temperatures and dry air, he said.