"put in the ground to grow," Old English plantian, from Latin plantare "to plant" (see plant (n.)). Reinforced by cognate Old French planter. Without reference to growing, "to insert firmly," late 14c. Of colonies from c. 1300. Figuratively, of ideas, etc., from early 15c. Meaning "to bury" is U.S. slang from U.S., 1855. Related: Planted; planting.
Old English plante "young tree or shrub, herb newly planted," from Latin planta "sprout, shoot, cutting" (source of Spanish planta, French plante), perhaps from *plantare "to drive in with the feet, push into the ground with the feet," from planta "sole of the foot," from nasalized form of PIE root *plat- "to spread."
Broader sense of "any vegetable life, vegetation generally" is first recorded 1550s. Most extended usages are from the verb, on the notion of "something planted;" such as "construction for an industrial process," 1789, at first with reference to the set-up of machinery, later also the building; also slang meaning "a spy" (1812). Many of these follow similar developments in the French form of the word. German Pflanz, Irish cland, Welsh plant are from Latin.