By Mark Henderson, Times Online via Checkbiotech

Scientists are taking on the challenge of climate change to ensure that gardeners will still be able to grow the traditional blooms of an English country garden in a warmer world.

The hot, dry, Mediterranean climate forecast for much of Britain as temperatures rise over the coming decades threatens many common plants, such as busy lizzies, begonias, pansies and primroses, which prefer mild and damp summers.

Plant breeders, however, are developing new varieties of old favourites that will thrive in a warmer and dryer climate.

In the short term, these heat-loving begonias and busy lizzies are aimed at the horticultural market in countries such as Spain and Italy, but they also promise to allow British gardeners to carry on planting their favourites long into the future.

Marjan Vlam, of Syngenta, a biotechnology and seed company that is developing new varieties at its laboratory and nursery in Enkhuizen, near Amsterdam, said: “It is one of the nicest side-effects of the work we are doing.

“By developing these varieties for sale today in the south of France, Greece, Italy and Spain, we are also developing varieties that can still be grown in the north of Europe as the climate gets warmer.”

Har Stemkens, a plant breeder at the nursery, said: “In 20 years’ time, gardeners will not be growing the same plants as they are today. Though they might look like the same begonias and pansies, they will be genetically different.

“The gardener doesn’t see this: he keeps buying the same plant, but it is a different plant from the one he bought a decade ago. It is invisible evolution that the customer doesn’t notice.”

Over the next 50 years, climate scientists expect average temperatures in Britain to rise by between 2C and 5C (3.5 to 9F) in summer and by between 2C and 3C in winter. This will open up British gardens to exotic species such as bougainvillea, strawflowers and mimosa, but it will prove too much for some native plants, Mr Stemkens said.

The Syngenta team takes varieties of a flower that it wants to improve to its warm-weather breeding centre near Avignon and picks out the plants that survive longest and produce the strongest blooms. The most successful varieties are then cross-bred with one another in conventional fashion, and the process starts over again.

“It is like natural selection, only it is us and not nature that decides which plants to breed from,” Mr Stemkens said.

The Enkhuizen test fields feature dozens of flowering plants that have been adapted for warmer conditions, including rows of taller, heat-tolerant begonias and busy lizzies that can thrive in direct sunlight and with less moisture than is usual.

Annemarie Houbraken, who is another nursery breeder, was recently awarded the gold medal of the ornamental plant industry body for developing the Molimba ‘Mini White’, a bushy daisy that can flower continuously through the summer months without yellowing.

A new speciality likely to be available next year is a line of purple and yellow viola flowers - smaller relatives of the pansy - that bloom throughout the summer. Most viola varieties do not survive beyond June or July because of the heat.

Other varieties that help gardeners in different ways are also on the agenda. Mr Stemkens has developed a verbena that produces virtually no seeds, so cutting out the chore of dead-heading.

Copyright 2005 Times Newspapers Ltd.