How to Sow and Grow Celeriac: A Complete Guide

Celeriac is a long-season relative of celery grown for its swollen, knobbly stem base. It develops slowly at first and then enlarges through late summer and autumn. Early sowing, rich soil and steady moisture are essential.

Choosing varieties

Modern smooth-rooted varieties are easier to clean and often mature earlier. Choose bolt-resistant cultivars for cool springs and varieties with good storage quality where winter use is important.

When and how to sow

Sow from late winter to early spring. Press tiny seed onto moist peat-free compost and barely cover because light aids germination. Keep at 18–21°C and maintain surface moisture. Germination may take two to three weeks.

Pricking out and planting

Prick seedlings into modules when large enough, keeping the crown visible. Pot on if needed and harden carefully. Plant after frost, 30–40 cm apart, with the growing point at soil level. Planting too deeply can prevent a good swollen base.

Soil and feeding

Use deep fertile moisture-retentive soil enriched with mature compost. Incorporate a balanced organic fertiliser on poor ground. Celeriac benefits from regular nutrients but not excessive nitrogen, which creates leaf at the expense of the swollen stem.

Watering and mulching

Water deeply throughout summer and mulch after soil warms. Drought produces small fibrous roots. In containers, use at least 25–30 litres per plant and check moisture daily in hot weather.

Root care

As the swollen base enlarges, remove only the lowest old leaves and rub away small side roots from the upper crown if desired. Do not strip healthy foliage heavily because it feeds the root.

Common problems

• Bolting: protect young plants from prolonged cold and transplant without severe checks

• Small roots: sow early, space adequately and maintain moisture and nutrition

• Celery leaf miner: remove mined leaves and use mesh

• Septoria leaf spot: rotate crops, improve airflow and avoid overhead irrigation

• Hollow or brown centres: avoid irregular moisture and excessive growth from heavy feeding

Harvesting and storing

Lift celeriac from autumn once roots reach a useful size. It tolerates light frost, but protect or lift before severe freezing. Trim leaves and fine roots. Store sound roots in cool humid conditions, boxes of damp sand or the refrigerator. Celeriac also freezes well after blanching.

A reliable approach

Sow early, keep the crown at soil level and prevent drought throughout the long growing season. Patience matters: much of the swelling occurs late in the year.