Celeriac

Celeriac (Apium graveolens var. rapaceum) is a root vegetable grown for its swollen, bulb-like hypocotyl with an intense, earthy celery flavour. The flesh is white, dense, and aromatic, retaining its colour even after cooking. It requires a long growing season and must be started indoors well ahead of transplanting. Full sun and consistently moist, fertile soil produce the largest, smoothest roots.

Growing

Sow seeds at a soil temperature of 18–22 °C, pressing them only 2 mm into moist compost — seeds require light to germinate. Start indoors 10–12 weeks before transplanting outdoors. To speed germination, soak seeds in lukewarm water for 24 hours, pat dry, then sow. Germination takes 14–24 days. Once seedlings are established, provide maximum light and lower the temperature slightly. Harden off transplants thoroughly before moving outside. Space plants 25–40 cm apart in rows 50–60 cm apart once nights reliably stay above 5 °C.

Care

Keep soil consistently moist — celeriac is sensitive to drought, which causes hollow or split roots. Feed with a balanced fertiliser every two to three weeks during the growing season, switching to a lower-nitrogen formula once roots begin to swell. Remove outer leaves that shade and crowd the crown, and snap off any side shoots that form on the hypocotyl to encourage a clean, round bulb. Earth up the root slightly if it pushes above the soil surface.

Harvest

Harvest when roots reach at least 10 cm in diameter and the skin is firm. The root can remain in the ground after light frosts, which often improve flavour. Lift with a fork, cut leaves to a short stub, and brush off excess soil. Varieties range from 100 to 115 days to maturity; a harvest window of up to 60 days is possible with staggered sowings or multiple varieties.

In the kitchen

Peel thickly to remove the rough outer skin, then slice, dice, or grate. Use raw in remoulade or slaws, roast in wedges with olive oil, purée into soups, or simmer in stews. Blanch immediately in lemon water if serving raw to prevent discolouration. The leaves are also edible and add celery flavour to stocks and salads.

Storing

Store unwashed roots in a cool (0–4 °C), humid environment — a root cellar, perforated bag in the refrigerator, or buried in just-damp sand. Properly stored roots keep for 3–6 months. For longer preservation, blanch and freeze diced celeriac for up to 12 months, or pickle in vinegar brine.