The English country garden is unlikely to survive in the South East beyond the next 100 years, scientists say.
Fields of sunflowers could replace the traditional English landscape
Climate change means the rolling lawns and herbaceous borders of Surrey, Kent, Hampshire and Sussex may be replaced by olive groves and grape vines.
Global warming is being discussed at a Royal Horticultural Society conference at Guildford's University of Surrey.
Experts say summer temperatures in the South East are expected to be up to 3C warmer by 2050 with 35% less rainfall.
If the current rate of warming continues, summers could be as much as 6C warmer by the 2080s, the scientists say.
"Lawns and herbaceous borders are going to be difficult to maintain, especially in areas of water shortages," said Guy Barter, from the Royal Horticultural Society.
"For the average gardener there may be more opportunities but it's going to be very difficult for the National Trust, for example, to maintain the character of its historic gardens."
Parts of England could resemble the Mediterranean scenes painted by Vincent Van Gogh, with fields of sunflowers becoming common features along with palms, shrubs and eucalyptus.
"It's already happening - you can already see fields of sunflowers," said Professor Jeff Burley, from Oxford University.
Levels of sunlight are lower in England than in the Med, but many plant and tree species found in southern France are expected to become more common further north.
They include walnut, poplar, sweet chestnut, plums, kiwi fruits and vines, the scientists say.
Native woodlands of oak, beech, ash and Scots pine are expected to survive, but beech woodlands are likely to be hit hard in counties such as Kent and Sussex.
Burnham Beeches, a small patch of ancient woodland in Buckinghamshire, is owned - perhaps surprisingly - by the Corporation of London.
In the 1880s, it bought up the land to allow Londoners a green and pleasant space to enjoy what is effectively a day out in the countryside.
But forestry experts ay that the beeches that made Burnham famous may one day no longer exist.
"It's a real problem for us," said Helen Reid, conservation officer at Burnham.
"Some of the older trees have been here for 500 years, which gives you an idea of how far ahead you have to plan when you're trying to manage woodland."