His father remarried Mary Haygarth and emigrated to Durban, and John, who had spent seven years at sea after leaving school, joined him there in 1852.

Here he developed an interest in cryptogams and started collecting ferns, mosses and fungi as well as flowering plants.

As a result of his growing interest in botany, he accepted the post of curator of the Durban Botanic Gardens in 1882.

From his interest in crop plants, he established the suitability of Uba sugar cane (Saccharum sinense L.), for conditions in Natal.

He is commemorated in the genera Woodia Schltr., Woodiella Sydow and a large number of species names including that of Encephalartos woodii Sander, which he first discovered.