This year's focus piece is a giant multi-tone sugar maple leaf which will take pride of place on the hill opposite the visitor centre in the sugar maple forest.

More than 200 hand-knitted scarves in yellows, ochres and reds were artfully placed to create the work, but Warm Tree Convenor Jocelyn Plovits and her team have installed more cheeky and creative designs in other areas.

"It keeps the colour of autumn in the arboretum for much longer than nature was able to," she said.

"Some of the scarves used to form the veins of the leaf are seven to 12 metres long. We have to count it all properly but we are setting the bar for the biggest knitted autumn leaf."

Fifty Himalayan Cedar trunks have been adorned with colourful scarves as have many of the Camden White Gums on Dairy Farmers Hills and the seat in the Southern Tablelands ecosystem park will have a cosy knit cover.

But with the big stuff comes the little.

"We have tiny scarves on the trunks and branches in the National Bonsai Collection – they are so cute!" she said.

The curator of the Bonsai area helped to install the knitting to make sure the arty colour didn't impact the brown of the miniature plants.

The showcase with the maple leaf motif will be launched on July 1, a Canadian national day, by the Canadian High Commissioner to Australia.

There is a school program run in conjunction with the month-long Warm Trees exhibition and a photographic collection of images from Canada will be on show for visitors too.

Last year the knitting was used to create blankets to keep the homeless and vulnerable warm and this year the knitted pieces will be transformed into winter dog coats for rescue animals at the ACT Domestic Animal Service.

Ms Plovits said each year the numbers of donations from knitters across the capital grew allowing organisers' wild and creative ideas to flourish.

"Knitters have come from all over the place," she said. "This year we had children donating, a group from Mirinjani nursing home and a group of bridge players in their 90s who donated 50 scarves in their own right."

But get your winter woollies on and get out there, she warned.

"It will be there for a month and then it is gone again."