also dead-wood, 1887 in the figurative sense of "useless person or thing," originally American English, from dead (adj.) + wood (n.). The meaning "wood dead upon a tree" is by 1803. Dead wood in a forest is useful as firewood; perhaps the reference here is to the dried up parts of plants grown for commercial production of flowers or fruit.
The term also meant, in ship-building, "timber built up at either end of the keel to afford firm fastening for the cant timbers" (18c.) and, in bowls, "pins which have been knocked down and block those still standing" (1858).