Water Needs and Irrigation of Blackberries

Blackberries have a shallow root system, and a regular (consistent and sufficient) water supply (irrigation) is needed to produce fruits of good size and quality.

When is it most important to water blackberries?

You can aim at keeping the upper 8-10 inches (20-25 cm) of soil moist enough and adjust the amounts of water needed depending on the soil type, environmental conditions, and physiological stage of the blackberry plants. However, remember that blackberries are very sensitive to water lodging and the lack of root oxygen. Such conditions may lead to the weakening of plants, decreased productivity, increased disease susceptibility, root rots, and, in extreme situations, even plant death.

Always water thoroughly after planting and apply regular irrigations until the crop has successfully been established. Water is needed mostly from flowering until fruit enlargement, which is the ripening of blackberries (critical stages) to maximize the yield. Generally, blackberries need 1-2 in (25-50 mm) of water weekly during that period. During the fruiting stage or hot and windy conditions, greater amounts and more frequent applications (e.g., once every 4 days) of water should be applied to help the plant withstand the stress and maximize the size and quality of the fruits. Finally, you can add mulch around the plant's base to prevent excessive water evaporation and insulate the roots. Appropriate weed management should be performed, especially in young plantations, to reduce the water losses from the antagonistic plants.

How to irrigate blackberries?

The 2 main irrigation systems used in blackberries are drip (or trickle) and overhead sprinkler systems. While some farmers may use it, overhead irrigation (with sprinklers) has relatively low efficiency (70%) and promotes fruit rot and leaf diseases. Hence, it is not recommended for blackberries, especially when grown in high tunnels. However, sprinkler irrigation can be used to reduce the risk of frost damage to the plants.

On the other hand, drip irrigation is more effective (up to 95%), requires less labor, and allows the simultaneous supply of water and nutrients (fertigation). However, the cost of establishment and maintenance is relatively high. The biwall tubing or ¾-inch poly tubing that can be used may be placed above or below the ground, with the drippers 1.5-3 feet (45-91 cm) apart. When using drip irrigation, blackberries should be watered daily for 1 to 2 hours, longer in hot weather or when the fruit ripens. Generally, water is needed 2-3 times a week, depending on the climate conditions, from the end of spring until mid-fall (mid-May through October). During the plants' dormancy period (end of fall until early spring), irrigation can be interrupted since the plants' needs are minimal, and the rainfalls are usually sufficient to cover them.

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Further reading