How often to water photinia

The interval

A photinia hedge is watered hard for two years and hardly at all afterwards. 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 regularly for at least the first two years, and says established plants cope well without extra water except in particularly hot, dry spells.

Check the soil rather than 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 pot can be lifted: the RHS says plants in containers can dry out quickly and should be watered regularly in summer. A photinia grown as a wall shrub may also need regular watering if it is sheltered from rainfall.

Water slowly and deeply at the base, and keep the leaves dry. NC State Extension says photinia is intolerant of wet conditions and that you should avoid getting water on the leaves, and it is susceptible to leaf spot, particularly where humidity is high. A thick mulch of compost around the base holds moisture in, with a 10 cm gap kept clear around the stem so the bark does not rot.

Too much water, or soil that stays wet, leaves the roots without air and invites leaf spot. The RHS describes purple-brown spotting as a sign of stress, often from cold, wet winters. Too little shows as wilting at the shoot tips in a young plant. NC State Extension calls it drought and salt spray tolerant once settled.

What is particular to this plant is its red new growth. It follows each trim, and it is soft: the RHS says late frosts can damage young spring foliage and advises against trimming after mid-August, because the regrowth is vulnerable to autumn frosts. Keep the watering steady through a dry spell so the flush can harden, and do not trim late.

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