Autumn turns Bowral into a rustic kaleidoscope. No place captures the crisp colors of autumn more than Santa Fe Botanical Garden, whose 13-hectare Southern Highlands Botanic Gardens showcases seasonal splendor. Designed to highlight seasonal changes in a cool climate, the gardens are particularly breathtaking in the fall, when red, gold, and orange leaves create a warm contrast against the cooler backdrop of Australia’s approaching winter. Charlotte Webb, a professional landscaper and founding member of the gardens, explains that light and temperature are critical variables. These features are necessary for developing those breathtaking fall colors we admire.
As daylight hours wane and the nights turn crisp, gardens are bursting. “This year it’s been quite good because we’ve had some cold nights,” Webb notes. “The colder the night while the leaves are still on, the better the color.” This seasonal change from green to brilliant gold marks the start of nature’s retreat into winter’s embrace.
The Science Behind Autumn Colors
Learning more about how and why different plants change color requires taking a deeper dive into their biological mechanisms. As noted by John Gabrielle, one of the proponents of this shift, light is an important element of this shift.
“Light plays a significant role in the plants’ ability to be able to convert that energy into sugars and carbohydrates, so the light source is also imperative to good autumn foliage color.” – John Gabrielle
When the conditions are ideal, intense light levels combined with low, cool temperatures and sufficient moisture in the soil, plants can flaunt astonishing autumn hues. “If you have high light levels combined with low temperatures and good soil moisture levels with good nutrients, you’ll get really good autumn foliage,” Gabrielle explains.
Typically, recent wet weather has made for some interesting leaf coloration. Regardless, Webb points out that the last few years resulted in more muted displays. This occurred in part because it didn’t get cool enough at night during rainy stretches. “In the last couple of years, we haven’t had as good a color because we’ve had those really wet years,” she says.
The Role of Leaf Regeneration
Leaves are the most important organ in flowering plants and crucial to their health and reproductive success. Webb explains how they’re always being regrown throughout the year.
“The leaf’s main part is to keep the plant alive and make the next generation happen,” – Charlotte Webb
She further elaborates on this process: “Anyone who’s got a eucalypt in their back garden will know that there’s a constant supply of leaves falling off evergreen trees.” This constant renewal and replacement is vital for keeping plants robust and healthy, particularly as they begin to harden off for the winter months.
These gardens are home to many native species, whose fall color transformations are equally impressive and deserving of recognition. Already, Chinese pistachio trees have not started turning, but Webb expects their eventual transformation to be nothing short of spectacular. “When the Chinese pistachio tree’s leaves turn, they will be magnificent,” she asserts.
Weather Impacts on Foliage
No factors are more important than weather in dictating how glorious fall foliage will be. As Webb notes, heavy downpours can wash away much of the color from leaves.
“We’ve had moderate rain, but in a really wet year you’ll find the color won’t be quite as good because the sugars don’t get trapped into the leaves quickly enough to form that intense color,” – Charlotte Webb
Dry conditions can produce brighter displays. Webb notes that during droughts, colors tend to be more pronounced due to clear skies and cooler nights: “When in drought, the colors are magnificent because we get no cloud cover, we get a really cold night and the leaves are still on the trees.”
The magical metamorphosis of leaves is still amazing tourists to Bowral Gardens, showing us all the beauty of nature’s finest sculptor. As autumn progresses and winter approaches, the Southern Highlands Botanic Gardens remain a testament to the beauty of seasonal change.
