Geranium in Night Window demonstrates Knaths's early style, which reveals the influences of European modernism prior to his later explorations of cubism. Knaths's personal vision is apparent, shown in his vigorous and expressive use of color to reveal the mystical qualities of nature.
Knaths employs the motif of flowers in a window, a theme he perhaps appropriated from Henri Matisse; here, in emulating the French master, Knaths creates tension by distorting perspective. He combines flat decorative elements (such as the broad contours of the leaves and the daubs of paint forming the curtain design) with cool planes of color receding into space (such as the shelf supporting the plant). The spatial depth implied by the window's niche is counterbalanced by the curtains, which hang parallel to the picture plane. Certain evocative qualities are reminiscent of Marc Chagall, whose works Knaths also admired in the early twenties. The cloth on the shelf, with its floating dots, and the window's wood mullions, which form a cross that floats against the deep-purple night sky, create an aura of mystery that recalls Chagall's dream-like images.
Knaths was first introduced to European modernism when he was a guard for the Chicago venue of the 1913 Armory Show. By his own admission, he was confused by the exhibition's "radical" art, but was immediately awed by Cézanne. After moving to Provincetown, Knaths gained greater familiarity with the European avant-garde through the influence of his future wife, Helen Weinrich, and her sister, Agnes, both of whom had spent many years in Paris. Knaths never visited Europe, which was unusual among early American modernists, despite the strong influence of European modernism upon his art. An avid reader on philosophy, art, and art theory, he visited numerous New York galleries and museums in the early 1920s. Knaths quickly learned to combine the expressive qualities of color with his new understanding of pictorial space.
Duncan Phillips most admired the lyrical qualities of Knaths's paintings. On Geranium in Night Window he wrote: "This exceptionally promising canvas reveals a delightful sense of color relations and a developed knowledge of what happens to colors under a flickering play of light."