A deciduous plant is one where parts (such as leaves) are dropped off the plant when they are no longer needed. The plant does this to conserve energy, rather than holding on to parts which have no purpose anymore. Many trees are deciduous, and their leaves fall of each season.
But what about grapes? Are grape vines deciduous?
Yes, they are!
The unused parts of the grape vine will fall of each season, and new ones will grow in during the next growing season. You can help the plant along by pruning it yourself, if you want your grape vines to produce at maximum capacity.