Caring for English Oak

English oak is a low-maintenance tree once its roots are established, typically after two to three years. Water young trees regularly during dry spells in the first two growing seasons—give a thorough soak every 10–14 days rather than frequent light watering, applying 30–40 litres per session to encourage deep rooting. Established oaks are drought-tolerant and rarely need watering except during prolonged summer droughts, when a deep monthly soak is beneficial. Feed young trees in March and April with a general-purpose granular fertiliser (such as blood, fish and bone) scattered in a circle around the drip line and lightly forked into the soil surface. Mature oaks do not require regular feeding; a 5 cm top-up of compost or leaf mould as mulch every other spring provides sufficient nutrients. Keep a mulch-free collar of about 10 cm around the trunk itself. Oak is generally robust but can suffer from oak processionary moth caterpillars (a notifiable pest—contact your local authority if you see silken nests on branches in late spring), powdery mildew (white coating on leaves, mostly cosmetic), and acute oak decline (bleeding lesions on the trunk). Chronic oak decline, caused by various stresses, shows as progressive dieback; maintain good soil conditions and avoid compacting the root zone to reduce risk. Knopper galls and marble galls on acorns and leaves are common but harmless. In autumn, allow fallen leaves to remain under the canopy where possible—they return nutrients and support beneficial fungi essential to oak health.