"series of people or things in a more or less straight line," Middle English reue, from late Old English reawe, rewe, earlier ræw "a row, line; succession, hedge-row," probably from Proto-Germanic *rai(h)waz (source also of Middle Dutch rie, Dutch rij "row;" Old High German rihan "to thread," riga "line;" German Reihe "row, line, series;" Old Norse rega "string"), which is possibly from PIE root *rei- "to scratch, tear, cut" (source also of Sanskrit rikhati "scratches," rekha "line").
The meaning "a number of houses in a line" is attested from mid-14c., according to OED chiefly Scottish and northern English. The meaning "line of seats in a theater" is by 1710. The meaning "line of plants in a field or garden" is by 1733, hence the figurative phrase hard row to hoe attested from 1823, American English.
"propel (a vessel) with oars or paddles," Middle English rouen (mid-14c.), from Old English rowan (intrans.) "go by water, row" (class VII strong verb; past tense reow, past participle rowen), from Proto-Germanic *ro- (source also of Old Norse roa, Dutch roeien, West Frisian roeije, Middle High German rüejen), from PIE root *ere- "to row." The figurative phrase row against the flood "attempt what is difficult" is from mid-12c. The muscle-building rowing-machine is attested by 1848.