🌱 Celeriac

Celeriac is a knobbly root with a smooth, nutty, celery-like flavour, and it is one of the most useful winter vegetables for soups, mash and the French salad céleri rémoulade. It is not difficult but has a long growing season and needs a good start indoors.

Celeriac loves a fertile, moisture-retentive soil and regular watering. In return it will stand in the ground through most of the winter, so it is a handy crop for a medium or large plot that wants late-season produce.

Varieties to try

Prinz (reliable, smooth roots)Monarch (large and well-flavoured)Brilliant (good stored quality)Giant Prague (traditional and heavy cropping)

Sow in March to early April in seed trays of moist, peat-free seed compost, pressing seeds onto the surface without covering, as they need light to germinate. Keep at about 15–20°C in a propagator or warm windowsill. Germination can take two to three weeks, so be patient.

Prick out seedlings into individual small pots when they have two true leaves, harden them off in May and plant out in late May to June, 30–40 cm apart each way. Plant with the base of the stems at soil level or slightly above, as burying the crown gives misshapen roots.

Top tips

• Do not cover the seed; it needs light to germinate.
• Keep warm and moist until seedlings appear.
• Harden off over two weeks before planting.
• Plant with the crown at soil level, never buried.

Water frequently and generously throughout summer: dry spells make celeriac woody and hollow. Mulch with compost or grass clippings to hold moisture, and feed every two to three weeks with a general liquid fertiliser. Remove any side shoots and the lowest leaves in late summer to expose the shoulders of the root.

Slugs are the main nuisance when plants are young, and celery leaf miner and celery fly can damage the foliage; pick off affected leaves. Celeriac is fairly hardy, but a thick mulch of straw protects the roots in cold winters.

Top tips

• Never let the soil dry out.
• Remove the lowest leaves in late summer.
• Feed every few weeks during summer.
• Mulch heavily with straw in hard winters.

Watch out for

SlugsCelery leaf minerCelery flyCarrot fly

Roots are ready from October and size up through autumn, reaching 10–15 cm across. They are hardy and can stay in the ground, but lift before severe frosts or cover well with straw. Use a fork to loosen the soil, then lift and trim off the leaves and fibrous roots.

In mild areas, harvest as required until March. Roots left after that will start to produce a flower stem and become woody and hollow, so lift any remaining ones by early spring.

Top tips

• Cover with straw for winter harvesting.
• Lift before the soil freezes hard.
• Trim off leaves and roots before storing.
• Larger roots are not always better; check for hollows.

Peel off the knobbly skin, cut into pieces and put straight into water with a squeeze of lemon, as it browns quickly. Celeriac makes a creamy soup, an excellent mash with potatoes, a golden roast, or a crisp raw salad shredded in mustard mayonnaise. It also adds depth to stews and gratins.

Trimmed roots keep for two to three months in boxes of slightly damp sand or compost in a cool, frost-free shed, or for several weeks in the vegetable drawer of the fridge. Cubed and blanched for three minutes, they freeze well, as does celeriac soup.

Top tips

• Drop peeled pieces into acidulated water to stop browning.
• Use a sturdy knife to cut off the skin.
• Roast cubes with garlic and thyme.
• Mash with potato for a lighter, nuttier purée.