The early work of herman de vries includes collages of found material, such as a layer of posters torn off the wall. He uses the term 'collages trouvés' for this, referring to Marcel Duchamp's 'objets trouvés'. Later in the 1950s, he starts painting in white, grey and black tones. These loose, representationless works can be classified as matter painting. Around 1960, de vries works only with white paint. His early work is thus close to the Informal art of the same period.
In 1961, together with Armando and Henk Peeters of the Nul group, de vries founded the magazine nul = 0. After two issues, however, the editors disbanded and de vries continued the magazine for two more issues on his own. Meanwhile, he exchanged his job as a botanist for an appointment as a biological researcher at the Institute for Applied Biological Research in Nature (ITBON) in Arnhem. In his work, he now uses probability as an important visual tool. This produces works with randomly placed blocks, dots and letters.
In 1970, de vries moved to the Bavarian village of Eschenau (near Knetzgau) and from this time on, nature and Eastern ways of thinking became important elements in his work. Change and temporal arrangements as they prevail in nature are expressed, for instance, in works with fallen tree leaves or in a report of a survey of plants found on a fenced-off piece of meadow.
Since the 1980s, the emphasis in his work has been on the disturbed relationship between man and nature, which, according to de vries, threatens to cause the loss of an important source of knowledge. In books, he documents a large collection of herbs and crops, in works on paper he uses different kinds of earth as pigment and also exhibits grasses, fragrant rose petals and plants with hallucinatory effects. Besides a large number of artists' books, de vries also makes photographs, films and text works. This work in particular received special attention during the Venice Biennale in 2015, when herman was given the solo exhibition 'to be al ways to be' in the Dutch pavilion, curated by Colin Huizing and Cees de Boer.