Caring for Fennel

Fennel has moderate water needs and performs best with consistent moisture, especially during dry spells in summer. Water deeply once or twice a week rather than little and often, encouraging roots to grow down into the soil. In prolonged dry weather, increase watering frequency; stressed plants may bolt prematurely or develop bitter-tasting foliage. Reduce watering in autumn as growth slows, and avoid waterlogging over winter. Feed fennel once in April as new growth begins. Apply a balanced general-purpose fertiliser or scatter a handful of blood, fish and bone around the base of each plant, then water in well. Avoid high-nitrogen feeds later in the season, as these promote soft, leafy growth at the expense of flavour and hardiness. A spring mulch of garden compost or well-rotted manure provides slow-release nutrients and helps retain soil moisture through summer. Fennel is generally trouble-free, but aphids can cluster on young shoots and flower heads in warm weather. Squash small infestations by hand or spray with an organic insecticidal soap. Slugs occasionally nibble seedlings; protect young plants with grit or organic slug pellets. Powdery mildew may appear on foliage in dry summers; improve air circulation by thinning congested growth and water at the base rather than overhead. Established fennel is fully hardy in zones 5–10 and needs no winter protection in temperate Europe. The crown survives frosts and reshoot reliably in spring. Mulch around the base in late autumn to insulate roots in colder gardens, but avoid smothering the crown itself.