Caring for Gladiolus

Gladioli have moderate water needs and perform best with consistent moisture during active growth and flowering. Water regularly during dry spells from late spring through summer, aiming to keep the soil evenly moist but never waterlogged. In hot, dry weather, water deeply once or twice a week rather than little and often, directing water at the base of the plants to avoid wetting the foliage and flowers, which can encourage fungal disease. Reduce watering once flowering finishes and foliage begins to yellow. Feed gladioli in March, just as new growth emerges, with a general-purpose granular fertiliser such as blood, fish and bone or a balanced NPK feed. A second light feed with a high-potash tomato fertiliser in early summer, as flower spikes begin to form, encourages strong blooms. Avoid high-nitrogen feeds later in the season, as these promote soft foliage at the expense of flowers and corm development. Gladioli are susceptible to thrips, tiny sap-sucking insects that cause silvery streaking and distortion on leaves and flowers, particularly in hot, dry summers. Inspect plants regularly and, if necessary, spray with an appropriate insecticide in the evening to avoid harming pollinators. Gladiolus corm rot and fusarium wilt can occur in poorly drained or overly wet soil; always plant in well-drained sites and inspect stored corms before replanting, discarding any that feel soft or show dark patches. In zone 7 gardens, gladioli are not reliably hardy. Lift corms after the first autumn frosts and store them frost-free over winter as described in the pruning section. Mulching in situ is rarely sufficient protection in colder or wetter regions.