Growing Butterfly Bush in a pot

Once established, butterfly bush has low water needs and tolerates drought well. Water newly planted specimens regularly through their first summer, especially during dry spells. Established plants rarely need watering except in prolonged drought, when a deep soak every fortnight is sufficient. Overwatering or poorly drained soil causes more problems than dryness. Feed in April and May to support the flush of spring growth and summer flowering. Apply a general-purpose granular fertiliser (such as Growmore or blood, fish, and bone) around the base at the manufacturer's recommended rate, then water in if the soil is dry. Avoid high-nitrogen feeds later in the season, as soft late growth is more vulnerable to frost damage. A 5 cm top-up of mulch in spring helps retain moisture and suppress weeds, but keep it away from the stems. Butterfly bush is fully hardy across temperate Europe (zone 5a–9b) and needs no winter protection. In severe winters the top growth may be killed back, but the plant usually regenerates from the base in spring. If this happens, simply cut away dead wood in March. Pests are rarely a problem. Occasionally you may see capsid bugs, which cause distorted leaves and shoot tips, but damage is usually cosmetic. Powdery mildew can appear on foliage in dry summers, especially on congested plants; good air circulation through thinning and correct spacing helps prevent it. Caterpillars sometimes feed on leaves—this is part of the plant's appeal to wildlife and seldom requires intervention. Remove any that cause significant damage by hand.