How often to water blackberry

The interval

A blackberry is thirsty in its first year and self-sufficient after it. Count on a deep watering about every 5 days through the growing season when there has been no rain, and about every 30 days in winter only if the ground is dry. Growing season means the warm, bright months from spring to early autumn, roughly March to September in the northern hemisphere and September to March in the southern. The Royal Horticultural Society advises watering well straight after planting and through prolonged dry spells in the first growing season, and says well-established plants should not need extra water.

Check the soil, not the date. Push a trowel blade or a finger 8 to 10 cm down beside the plant. If the soil there is dry and crumbly, water, and if it is cool and holds together, wait. A plant in a large container can be lifted: the RHS says plants in containers need regular watering throughout the growing season to keep the compost slightly moist, and a dry container is far lighter than a wet one.

Water slowly and deeply at the base, and then leave the plant alone until the soil has dried again. A mulch of organic matter 5 to 7.5 cm deep in early spring, as the RHS advises, holds moisture in, with a slight gap left around the base of the stems to prevent rotting. Plants For A Future notes that blackberry prefers moist soil and can tolerate drought, which fits a plant that grows in hedgerows and on waste ground.

Too much water, in soil that does not drain, leaves the roots without air. Too little in the first year slows the canes that will fruit in the second.

What is particular to this plant is that the canes fruit in their second year. Most garden cultivars fruit on the previous year's canes, so water that builds good canes this year pays off as berries next summer, and that is why the first season's dry spells matter most.

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