Customers must spend over $35 per order to qualify for the free delivery through Amazon Prime Now, Amazon said on Tuesday. If they want their food delivered in under an hour, they must pay $7.99.

“We’re happy to bring our customers in San Francisco and Atlanta the convenience of free two-hour delivery through Prime Now and access to thousands of natural and organic groceries and locally sourced favorites,” Whole Foods co-founder and CEO John Mackey said in a statement. “Together, we have already lowered prices on many items, and this offering makes Prime customers’ lives even easier.”

Adding Whole Foods deliveries to Amazon’s Prime Delivery underscores Amazon’s push to become a huge grocer. The tech giant bought Whole Foods last summer for $13.7 billion, and reduced the price of some of the high-end grocery chain’s products like organic Fuji apples to appeal to a broader base of customers.

In February, Amazon said that it would offer free, two-hour Whole Foods deliveries to Prime customers who live in Austin, Cincinnati, Dallas, and Virginia Beach, with the promise of more cities to come during the year. The new cities announced on Tuesday bring the number of metropolitan areas in the free delivery program to six.

Besides Amazon’s Prime Now delivery service, the company also operates a separate Amazon Fresh online grocery delivery service. Customers using that service must pay a $14.95 monthly subscription fee.

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In February, Yahoo News reported that Amazon was planning to merge Amazon Fresh with Amazon Prime Now.