Growing Cornflower in a pot

Cornflowers are low-maintenance plants with minimal water and feeding needs once established. Water newly sown seeds or young plants lightly during dry spells in spring, but once the roots have settled in, they tolerate drought well and rarely need supplementary watering. Overwatering or planting in poorly drained soil can lead to root rot, so err on the side of dryness, especially in summer. Feed sparingly. In March or April, scatter a light dressing of general-purpose granular fertiliser or a thin layer of well-rotted compost around the base of the plants. Avoid high-nitrogen feeds, which promote lush foliage at the expense of flowers. Cornflowers grow naturally in nutrient-poor soils, so over-feeding can make them leggy and prone to flopping. One feed per year is usually sufficient. Cornflowers are fully hardy across all temperate European zones and need no special winter protection. In fact, they can survive temperatures well below freezing. If you've sown in autumn, young plants will overwinter outdoors without issue. There's no need to mulch for frost protection, though a light mulch of garden compost in spring can help suppress weeds. Pests and diseases are rarely a problem. Aphids occasionally cluster on young shoots in late spring; a strong jet of water or an insecticidal soap will deal with them. Powdery mildew can appear in hot, dry summers or if plants are overcrowded—ensure good spacing and air circulation to minimise risk. Slugs may nibble seedlings in damp weather; use organic slug pellets or barriers if necessary. Otherwise, cornflowers are remarkably trouble-free and will often self-seed freely, returning year after year with little intervention.