He studied medicine at the University of Kiel, and botany in Jena with Christian Ernst Stahl (1848-1919), where in 1904 he received his doctorate.
Afterwards, he worked as an assistant to Robert Hippolyte Chodat (1865-1934) in Geneva, to Wilhelm Pfeffer (1845-1920) at Leipzig, and under Friedrich Oltmanns (1860-1945) in Freiburg.
During his career, he undertook study trips to the Balearic Islands, Corsica, Norway, Italy, the Caucasus region, Netherlands East Indies and Japan.
He also conducted phytophysiological research of chemotaxis and nastic movements, as well as ecophysiological investigations involving photosynthesis and respiration of marine plants.
From 1913 to 1917, he published five treatises on the fungal class Hymenomycetes: Other significant writings by Kniep include: With Friedrich Oltmanns, he was editor of the botanical magazine, "Zeitschrift für Botanik".