Celeriac develops a pitted and whorled exterior that, when peeled away, reveals a soft, creamy white interior with a mild, herbaceous flavor. This Mediterranean native is popular in Europe. Gardeners and cooks in the United States largely ignored it until recently, when it began appearing on menus as a classic French salad, coarsely grated and dressed with rémoulade, or in potato leek soup.
Celeriac, also called celery root or knob celery, belongs to the same species as the common celery grown for its stalks—but is easier to grow. A cousin of carrots, parsley, and parsnips, celeriac (Apium graveolens) is a long-season crop, taking a minimum of 115 days from seed to a harvestable knob up to 4 inches in diameter. It needs well-fertilized soil and consistent moisture throughout the growing season to prevent bolting, misshapen roots, or black heart, a calcium deficiency that riddles the interior with dark mottled lines. The attractive leafy tops form a low mound, remain green from spring until fall, and can be harvested sparingly to season soups and stews.
Celeriac’s mild flavor easily blends with and enhances other vegetables. It is a boon to those on a diet: Boil and mash the low-starch knobs with an equal measure of potatoes for a dish with fewer calories than mashed potatoes. For a refreshing salad to serve alongside a hearty entrée, grate or thinly slice celeriac, then toss with rémoulade, a mustardy mayonnaise seasoned with fresh chopped tarragon.
Cultivars vary slightly in size, days to maturity, and reliability. ‘Brilliant’ and the European cultivar ‘Diamant’ are commonly available.
How to grow:
Sow seeds indoors 8 to 10 weeks before transplanting outdoors in late spring. Keep soil moist and temperatures at 65°F to 70°F while seeds are germinating; they can take 2 to 3 weeks to emerge. Move seedlings outdoors when weather is settled, setting plants 6 to 8 inches apart in loose, fertile soil. To avoid misshapen knobs, take extra care not to disturb the roots while transplanting.
Several times during the long growing season, side-dress with nutrient-rich compost or organic fertilizer. Don’t allow the soil to dry out, yet avoid too much water, which may lead to rot and a browning of the interior. Harvest in the fall before severe frost, using a garden fork to lift the gnarly roots. Shake off the loose soil, snap off the tops, and store alongside potatoes or beets in the root cellar or a cool, dark place until ready to bring into the kitchen for cooking.
Photo: Thomas MacDonald