And you don't need to do anything special to get Sweetheart to work its re-fruiting magic. It's just as easy to grow as any other Blueberry, thriving in full sun in cool northern climates, afternoon or partial shade farther south and west. If you have other Blueberry varieties growing in the garden, no problem -- Sweetheart will actually probably set even more berries if planted near other varieties. It is quite cold-hardy, thriving with 750 to 800 chill hours.