His parents having relocated to Kroonstad, where his father was appointed school inspector, he boarded in Bloemfontein with his violin teacher, Victor Pohl, who was also well known as an adventure writer.
Thereafter he moved to the Cape and settled at Kalk Bay, initially renting but, in 1978, purchasing the historic house Liscard, which he restored in 1983 through the services of architects Revel Fox, John Rennie and Pat Riley.
Having worked for a time at Valkenberg Hospital as a clinical assistant, Du Plessis developed an interest in psychoanalysis; and his general practice at Kalkbay came to be augmented by his role in psychiatry.
Working closely with Marie Blomerus, Du Plessis served as editor of Wurm, Izwi and New Nation, as well as a Flemish periodical, Argo.
A significant new element in these later anthologies was the integration of illustrations in collaboration with a range artists: with Braam Kruger in Openbaringe van Johannes; Hugo Slabber in Engel uit die paradys; Judith Mason in Nagjoernaal; Jan Visser in Herakles by Valsbaai; and Gus Ferguson in Op Koueberg, in which du Plessis makes translations of Chinese verse.
Judith Mason promised, in a review of Openbaringe van Johannes, that "for the price of a good cabernet," one would be holding in one's hands "a book which is brutal and charming, outrageous and compassionate, sensual and sore, angry and immeasurably humane.
Amongst regular guests at one period were Robert Ardrey (until his death in 1980) and his actress wife (and widow) Berdine Grünewald, who had retired to nearby St James.
A very well attended service was held in the Holy Trinity Church Kalk Bay following his death, and his ashes were scattered from a small fishing boat in front of his beloved "Liscard".