Duke Northern Highbush Blueberry Duke - Early Season. Large berries, high yields, very firm / Great flavor - sweet/tart, Blooms late Cold Hardy, USDA Zones 4 - 8 Northern Highbush varieties are very cold-hardy, making them ideal for home gardens in cooler northern climates of USDA zones 3-8. Besides producing an abundant crops of flavorful blueberries, these plants make great landscape plants with lovely flowers in the spring, dark green foliage that looks beautiful all summer and stunning colors in fall. All northern highbush plants are self-pollinating, but will produce more berries if 2 varieties are planted. Free Shipping to most locations. We cannot ship to AK, HI, APO, US Territories, or areas considered remote without a freight surcharge. All plants are inspected for quality prior to shipment. Let us know upon arrival if you have any concerns regarding your plant's condition. If your temperatures are warmer than 89 degrees or colder than 20 degrees, please wait until temperatures improve before ordering. Scenic Hill Farm is a licensed Oregon nursery 1/25