His work belongs to the German Romantic tradition but maintains a strict Neoclassical precision. Kolbe earned the nickname "Oak Kolbe" because of his frequent depictions of ancient, gnarled trees. He often placed figures from classical idylls, such as Chloe or Damon and Phyllis, within dense, overgrown forests. These scenes create a sense of isolation and quietude. His technique involved dense cross-hatching to build deep shadows. This method makes his forests appear almost impenetrable.

Modern collectors value Kolbe for his unique botanical perspective. His prints do not treat the natural world as a backdrop. Instead, elements like the cascade or the fountain in the wood become the primary subjects. The large-scale foliage and dramatic contrasts of light and shadow suit contemporary interiors that favour monochrome art. His etchings provide a bridge between traditional pastoral themes and a modern focus on the physical textures of plant life.