Tulips bloom at Araluen Botanic Park ahead of the annual Tulip Festival. Photo: Sydney Fossilo.

The flowers may be the main attraction at Araluen Botanic Park’s Tulip Festival, but behind the scenes, warmer weather is making the traditional growing process more difficult.

More than 250,000 tulips are planted for the annual festival, which opened on September 4, after being delayed from its usual August start to allow more of the flowers to bloom.

Garden supervisor Remo Gerace, who has worked at Araluen for six years, said the warmer weather had changed when staff could begin planting.

“The temperature has to be below 10 degrees before we plant the bulbs,” Mr Gerace said.

“If it gets too hot the flowers grow and bloom too quickly, and don’t make it to the festival.”

The team previously started preparing the beds in March, so bulbs could be planted from May. Last year, planting was delayed until the end of June because temperatures were too high.

The Bureau of Meteorology reports Australia has warmed by an average of 1.55C since national temperature records began in 1910, while rainfall across south-west WA has declined by about 16 per cent between April and October since 1970.

At Araluen, the effects are already being seen in the timing and lifespan of the flowers.

Views across the gardens and grounds of Araluen Botanic Park. Photo: Sydney Fossilo.

Horticulturist Connor Mokrzycki has worked at the park for a year and said some late-flowering tulips had bloomed earlier than expected, which is a concern.

The warmer temperatures can also mean the blooms do not last as long.

Tulips open during warmer days and close as temperatures drop overnight. Mr Mokrzycki said hotter conditions can cause them to grow too quickly, meaning some flowers can be lost within a week instead of lasting around three weeks.

“Another issue, if the bulbs are planted during a warmer time, is that they don’t have time to establish roots before they start blooming, which means their display actually won’t be as nice as it could be in terms of colour, size and leaf growth,” he said.

Views across the gardens and grounds of Araluen Botanic Park. Photo: Sydney Fossilo.

The team plants early, mid and late flowering varieties to spread blooms across the festival period, but Mr Mokrzycki said warmer, drier winters could make maintaining that spread increasingly difficult.

“I would expect within 10 years, definitely based on how the winters are progressing, that if rainfall keeps diminishing, yes, it would be a shorter season, for sure,” he said.

For now, Araluen is adapting its planting schedule to the changing conditions. But if temperatures continue to rise and rainfall declines, keeping 250,000 tulips blooming when visitors expect to see them could become increasingly difficult.