What Month Do Grapevines Bloom?

Month of Bloom

• Spring is the common blooming period for grapes. The exact month the flowers emerge varies with the climate but could be as early as March in the South to May to early June in the North.

Time

• Expect the grape plant to bloom about two months after the plant emerges from dormancy and its leaves appear. This allows the gardener time for pruning before the onset of the blooms. Blooms occur on new growth. Pruning that limits new growth lowers yield but improves quality, while pruning practices allowing large amounts of new growth maximize yield but may reduce quality.

Temperature

• Warmer temperatures mean grapes bloom earlier. Cornell University notes that grapes bloom six days earlier now than they did in the 1960s. While this is a long-term average, local weather during the spring season also affects the grape. An unseasonably warm spring leads to grape blooms earlier than an unseasonably cold spring.

Insects and Pests

• The Western flower thrip and several other insect species pose a particular threat to grapes during the blooming period. Monitor the grape plants during the spring bloom for insect damage. While the Western flower thrip does its damage to the flower, thrips damage the grapes themselves as the fruit grows during the summer.