The Queensland city of Toowoomba boasts Australia's longest and proudest floral histories, but a new breed of green thumbs is having to get savvy and adapt to a changing climate.

Participants in the springtime Carnival of Flowers say seasons are shifting and the traditional "nana" gardens filled with fragile flowers may soon be a thing of the past.

"They're using better water-saving techniques and generally protecting their plants from the extremes that their gardens are starting to suffer," retired horticultural educator and avid Toowoomba gardener Mike Wells said.

Hotter and drier climate

The most distinct change Mr Wells and other gardeners have noticed is the increased unpredictability of winter rainfall and compression of spring.

"As a born-and-bred Toowoomba boy, when I was a kid, you could set your watch to the way weather behaved in winter," Mr Wells said.

Rainfall from July to September has decreased by 27 per cent and 9 per cent overall in the last three decades, according to the Bureau of Meteorology.

"By the end of September into October we're starting to get summer-like temperatures, so I think spring has been compressed," Mr Wells said.

Mr Wells said gardeners were planting seedlings for the carnival as much as a month later than they had in the past.

The anecdotal weather observations of Toowoomba's gardeners are backed up by objective science.

University of Southern Queensland climatologist Chelsea Jarvis said the Darling Downs region was experiencing less rainfall in summer and winter and rising temperatures.

"In winter those winter rainstorms that used to press north into southern Queensland and get the Darling Downs are not seeming to come as far north," she said.

"The number of consecutive hot days has actually doubled for spring and for summer."

The temperate climate and rich volcanic soils of the Garden City allows a wide variety of plants to be grown, but as harsher conditions become commonplace, that floral array is shrinking.

"They're looking for plants that will survive those tougher times, particularly the heat," Mr Wells said.

"What we're seeing is a reduction in annual flowers and plants because they do tend in some cases to use more water, so gardeners are starting to select more perennial plants that flower in spring."

'Nana' gardens under threat

Toowoomba's gardening community is adapting to these changes.

"They're becoming more adept at selecting plants but they're also becoming much better at creating the conditions in the garden so plants can survive better, and that is [to do with] soil, mulching and clever watering," Mr Wells said.

Leonie Chapman typifies the new breed of Carnival of Flowers gardener that is focused on conserving water and building resilience in their own backyard.

"I've got a mix of Australian natives and old school cottage things ... that everyone's Nana had in their gardens," Ms Chapman said.

Ms Chapman keeps chickens, makes her own compost and keeps her garden free of chemicals. 

"I let nature have its balance. If everything is happy and in harmony, then there's no one pest or disease that takes over and decimates everything," Ms Chapman said.

Ms Chapman said changing climate was, in a sense, pushing a cultural change away from the traditional cottage garden filled with delicate, annual flowers.

"There's a different breed of gardeners coming through, they're not as picture-perfect gardens, there's more of a personal style coming through," she said.

"I also think food and productive gardens will be more at the forefront."

Despite the gradual changes, Mr Wells said Toowoomba's gardeners were a hardy bunch.

"I don't think our mantle as the garden city of Australia is going to be lost anytime soon," he said. 

SOURCE: https://www.abc.net.au/news/2021-09-30/climate-change-changing-gardens-in-queensland-flower-capital/100500088