Caring for Oregon Grape

Oregon grape is a low-maintenance shrub once established, tolerating dry shade and neglect better than most evergreens. Water newly planted specimens regularly during their first spring and summer, especially in dry spells, but after the first year watering is rarely needed except during prolonged drought. The plant's low water requirement makes it excellent for difficult, dry corners under trees or beside hedges. Feed once a year in March with a general-purpose granular fertiliser such as Growmore or blood, fish and bone, scattered around the base at the rate recommended on the packet. Alternatively, top up the mulch layer with garden compost or well-rotted manure, which feeds the soil as it breaks down. Avoid high-nitrogen feeds, which promote soft growth at the expense of flowers and berries. Replenish mulch every spring to suppress weeds and conserve moisture, keeping it a few centimetres clear of the stems to prevent rot. Oregon grape is fully hardy across temperate Europe (zone 5a–9a) and needs no winter protection, though the evergreen foliage can bronze or purple in cold weather—this is normal and the leaves green up again in spring. Pests are rare. Occasionally you may see mahonia rust, which causes orange pustules on the undersides of leaves; remove and bin affected foliage and avoid overhead watering. Leaf spot can occur in very damp, shaded sites with poor air circulation—improve spacing and clear fallen leaves in autumn. Aphids sometimes cluster on new growth in spring; a strong jet of water or an insecticidal soap usually resolves the problem quickly.