Geranium was a type of flower on Earth.
The Fourth Doctor explained that it was terribly difficult to cultivate away from Earth, and that it was Charles Dickens's favorite flower. (AUDIO: The False Guardian)
The Mechonoids preparing Hesperus for human colonisation maintained a garden with geraniums. (PROSE: War of the Daleks)
The Eleventh Doctor had a red geranium, which he called Dave. (COMIC: Space in Dimension Relative and Time)