Lupin in August: monthly care

Prune lupins in July and August, immediately after the main flush of flowers fades. The primary task is deadheading: cut the spent flower spikes back to a side shoot or to just above the basal foliage using secateurs or a sharp knife. This prevents the plant from putting energy into seed production and often encourages a second, smaller flush of blooms later in summer or early autumn. If you want to collect seed for sowing, leave one or two spikes to mature; the pods will turn brown and split when ripe, usually by late August. In addition to deadheading, remove any yellowing or damaged leaves throughout the growing season to keep the plant tidy and reduce the risk of fungal disease, which lupins can be susceptible to in damp conditions. Cut these leaves back to the base of the stem. After flowering has completely finished in late summer, you can cut back the entire plant to ground level if the foliage looks tatty, though many gardeners prefer to leave the basal rosette of leaves intact over winter for a tidier appearance and some frost protection for the crown. Lupins are short-lived perennials, typically lasting three to five years. If clumps become congested or flowering declines, it's better to replace them with fresh plants rather than attempt rejuvenation pruning, as lupins don't respond well to hard cutting back of old woody growth. Always clean your tools between plants to avoid spreading disease.

Water lupins regularly during their first growing season to help establish the deep taproot, especially in dry spells. Once established, they have moderate water needs; water deeply during prolonged dry periods in spring and summer, particularly when buds are forming and during flowering. Reduce watering in autumn and winter, as lupins are dormant and excess moisture around the crown can cause rot. Feed in March and April as new growth emerges. Apply a balanced general-purpose fertiliser such as blood, fish and bone or a slow-release granular feed, scattering it around the base of the plant and watering in. Avoid high-nitrogen fertilisers, as lupins fix their own nitrogen through root nodules and too much can promote leafy growth at the expense of flowers. A light top-dressing of compost in early spring is also beneficial. Lupins are fully hardy in zones 4–8 and need no special winter protection in temperate Europe. Mulch around the base in autumn with compost or bark to suppress weeds and retain moisture, but keep mulch away from the crown. Common problems include aphids, which cluster on young shoots and flower spikes in spring—hose them off or use an insecticidal soap. Lupin anthracnose, a fungal disease causing brown spots on leaves and stems, can be serious; remove and destroy affected foliage promptly and avoid overhead watering. Powdery mildew may appear in dry summers; improve air circulation and water at the base. Slugs and snails target young foliage in spring, so use barriers or organic pellets if necessary.