A rolling strike of Starbucks baristas began Friday and grows to include about 300 of the coffee giant's shops across the U.S.

The Starbucks baristas strike is spreading to more cities — and the union organizing the workers warned the walkout would affect hundreds of stores on Christmas Eve, the last day of the five-day walkout.

Earlier, Starbucks said the union “prematurely ended” a bargaining session and called for talks to continue. The coffee chain has said it’s focused on improving workers’ experience and that baristas who work at least 20 hours a week receive $30 an hour, on average, when combining pay and benefits.