Nasturtium

Nasturtium (Tropaeolum majus) is a vigorous annual flower of cultivated, probably hybrid origin, producing vivid yellow, orange, and red blooms on round, lily-pad-shaped leaves with a distinctly peppery flavour. Plants range from compact mounding dwarfs to trailing vines reaching 3 metres, making them versatile for borders, containers, and hanging baskets. They thrive in well-drained, moderately lean soil — excess fertility encourages foliage at the expense of flowers. Both flowers and leaves are fully edible, and seeds can be pickled as a caper substitute.

Growing

Direct sow seeds 2 cm deep once soil temperatures reach at least 12 °C and nights remain reliably above 8 °C. Large seeds benefit from complete darkness during germination; cover pots or sow directly into the ground without disturbing. Space plants 25 cm apart for compact bushy varieties, or allow 50 cm between rows for trailing types. For an earlier display, sow indoors at 16–18 °C 3–4 weeks before outdoor planting, using individual deep pots to minimise root disturbance at transplant time. Avoid soggy or heavily manured ground — nasturtiums germinate and flower best in poor-to-average, free-draining soil.

Care

Water moderately; nasturtiums are drought-tolerant once established and overwatering causes lush foliage with few flowers. Do not feed with nitrogen-rich fertiliser. Pinch back trailing stems to encourage branching on compact varieties. Inspect regularly for blackfly aphids, which colonise the soft growing tips — remove by hand or use a strong jet of water. Deadhead spent blooms to prolong flowering throughout the growing period.

Harvest

Harvest flowers and young leaves continuously as they appear; picking encourages further production. Flowers are ready when fully open and brightly coloured. Harvest seeds for pickling when they are plump, green, and still soft — before they dry and harden on the plant. Plants flower prolifically from midsummer until the first frost kills the stems.

In the kitchen

Add whole flowers and torn leaves to salads, grain bowls, and cold plates for peppery heat and vivid colour. Stuff larger flowers with soft cheese as a canapé. Chop leaves into herb butters, dressings, and compound mayonnaises. Pickle immature seeds in brine or white wine vinegar for two to four weeks and use exactly as you would capers — in tartare sauce, pasta puttanesca, or scattered over smoked fish.

Storing

Fresh flowers and leaves are fragile; use on the day of picking or refrigerate loosely wrapped in damp paper for up to two days. Pickled seeds keep in sterilised sealed jars in a cool dark cupboard for up to six months. Dried seeds saved for sowing stay viable for three to four years in a cool, dry, airtight container away from light.