The centenarian arrived at Te Puna Quarry Park under blue skies in a 1930 Ford Model A.
With the sun beating down and birds singing, Alf slowly made his way up a gravel road to the planting site, surrounded by native bush and assisted only by his walking stick.
Friends and fellow volunteers gathered around and applauded as he dropped in the first spade-loads of soil.
"It's lovely," Alf said of the place chosen for his kauri. "It's a great little spot."
He has been a volunteer at the quarry park since 2002.
"It's been absolutely worthwhile coming out [here]," Alf said.
"It's the best thing that's ever happened to me while I've lived on my own."
He first came to the park to have a look around after his wife died of cancer and about 15 years later he is still driving himself to weekly get-togethers there - his driver licence has just been renewed for another two years.
Yesterday, the kauri planting was followed by just that, as well as morning tea and the cutting of birthday cake - fruit cake was Alf's preference over chocolate.