Carl von Effner, also Karl von Effner, Carl Joseph von Effner and Carl Effner (the younger) (10 February 1831 – 22 October 1884) was gardener to the Bavarian court, later Königlich Bayerischer Hofgärtendirektor ("Royal Bavarian Court Director of Gardens"), and landscape gardener.
Carl von Effner was descended from the Effner family, who for many years were gardeners in the service of the Bavarian royal court. He was great-grandson of the distinguished architect and builder Joseph Effner (1687–1745)
He was born as Carl Effner in Munich, son of Carl Effner (the elder) (1791–1870), Senior Bavarian Court Gardener. After a gardening apprenticeship he made various study visits to Vienna, Paris, England and Sanssouci, where he also became familiar with the "mixed style" of garden design of the well-known Prussian landscape architect Peter Joseph Lenné involving the formation of regular areas of formal ornamental garden within wider areas of landscaped garden, which enjoyed a revival in the mid-19th century.
On these study trips he was accompanied by Max Kolb, the later Inspector of the Botanical Gardens, Nymphenburg.
In 1857 Maximilian II recalled him to Munich and at the early age of 26 appointed him Court Gardener. From 1860 to 1865 he was active as representative of the Senior Court Gardener on the staff of the Obersthofmarschall. Maximilian made Effner responsible for the landscaping of the banks of the Isar between Haidhausen and Bogenhausen (later known as the Maximiliansanlagen, or Maximilian Gardens) and for the garden element of the Maximilianstrasse designed by Friedrich Bürklein.