The photo (found on Wikimedia Commons) is from the Album of Hongkong Canton Macao Amoy Foochow (digitized by National Institute of Informatics - Digital Silk Road Project). The album contains photos from 1870 (Amoy 1868).
This one shows the Botanical Garden and the Albany.
It's very similar to this one from 1868, but it was taken two years later.
On the one from 1868, the supports for young trees can be seen (you need the high resolution image from Hong Kong Public Library). They are gone in the 1970 one.