The Yield of Growing Blackberries

Age

• Blackberry fruit is an aggregate of drupelets that takes about 40 to 70 days to develop on plants following flowering. Blackberry plants begin producing fruit, to a limited degree, the year after planting. The first-year harvest typically yields no more than 2,000 lbs. of fruit per acre. Well-maintained plants will continue to produce crops up to 20 years; but in general, years three through eight are the blackberry plant's most productive years.

Site Selection

• Blackberry plants grow in U.S. Department of Agriculture hardiness zones 7 through 9. This warm-climate crop performs best under full sunlight in well-drained soil with a pH between 5.5 and 6.5. Avoid flood-prone sites and poorly drained soil. Sites must have good air and water drainage, as well as protection from strong winds. Temperatures less than 28 degrees F will damage tender blackberry blossoms; consequently, avoid low-lying frost-prone areas.

Water Management

• Adequate watering is the single most critical factor influencing primocane development, optimal fruit development and crop yields. Drought-like conditions before or during harvest can severely reduce the size and amount of crops, as well as the diameter of primocanes. The current-year fruit yield as well as the following-year yield is affected. The majority of moisture taken up by blackberries comes from the rooting zone of the blackberry plant, which is primarily in the top 6 inches of the soil. Provide at least 1 inch of water per day during the growing season, although significantly less water is required if drip irrigation is used.

Growth Habit and Type

• Blackberries are classified according to their growth habit, which includes erect, semi-erect and trailing types. Spacing, which impacts plant density and ultimately fruit yield, is cultivar dependent. Typically, erect and trailing blackberries are spaced 2 to 4 feet apart, within rows and 3 to 5 feet between rows. Recommended cultivars vary by area and growing conditions. The number of plants per acre can vary from as few as 400 to as much as 2,800.