Overview
- Name: Celeriac
- Botanical Name: Apium graveolens var. rapaceum
- Plant Family: Apiaceae
- Native to: Parts of Europe’s Mediterranean region
Description
Celeriac, also known as celery root, turnip-rooted celery, knob celery or German celery, is a cool-season biennial grown primarily for its crisp, celery-flavored, bulbous root. This knobby, globe-shaped root develops partially above the soil line and is actually a swollen stem base. Though celeriac is a biennial, it is usually cultivated as an annual and harvested after its first year, when the root reaches a good size. The plant typically grows to about 30–40 cm (12–16 in) and produces upright, green stems with leaves resembling parsley.
If allowed to mature through its second year and successfully overwinter, celeriac will sproduce small white umbels (the characteristic flower clusters of Apiaceae plants like carrots and parsley), eventually forming seed pods. However, it is not typically grown for these seeds. The spice known as celery seed generally comes from smallage—a wild variety of Apium graveolens—the same wild ancestor that gave rise to modern cultivated celery with its thicker, milder stalks and celeriac with its enlarged, edible root..
Celeriac is closely related to celery but is often considered easier to grow in cool, moist conditions. Its dense, fine-grained white flesh has a smooth, celery-like flavor and stores well. Celeriac can be eaten raw—grated or sliced into salads—or cooked in soups, stews, and other mixed vegetable dishes. It is particularly popular in European cuisine, where its versatility and distinctive flavor make it a staple in many recipes.
Interesting Facts
- Unlike many so-called “root” vegetables, celeriac is actually a swollen hypocotyl rather than a true tuber. Most of its edible mass develops just beneath the stem base rather than far underground, giving it a unique appearance and structure compared to other root crops.
- Beneath its rough, knobby exterior, celeriac has a mild, nutty taste. This contrast makes it a favorite among chefs seeking versatile cool-weather vegetables. Once peeled, it is often used in soups, purees, and even raw salads (when shredded or sliced thinly) for an appealing crunch and subtle celery flavor.
- Celeriac contains dietary fiber, vitamin C, and vitamin K, contributing to its status as a healthful addition to meals. Its relatively low starch content sets it apart from potatoes and other root crops, offering a lighter option for those mindful of their carbohydrate intake.
- Celeriac is closely related to traditional stalk celery but was historically grown mainly by European market gardeners. Over time, it found a prominent place in French cuisine—particularly in the classic dish “céleri rémoulade.” Today, it is globally recognized and continues to gain popularity among gardeners seeking alternative cold-hardy root vegetables.
Basic Growing Information
Celeriac is a cool-season crop that performs best in temperatures ranging from about 10–21°C (50–70°F). It needs a relatively long growing season and tolerates light frost, and is more frost-tolerant than celery, though prolonged exposure to temperatures below 7°C (45°F) can slow its development. In many regions, starting seeds indoors and transplanting outdoors after the risk of hard frost has passed is common.
Grow celeriac in much the same way as celery. Start seeds indoors about 10 to 12 weeks before your last expected frost. Plant several seeds per hole. Seeds need light to germinate, so don’t cover them deeply. About 50% germination is considered normal for celeriac. Keep the soil moist and warm at roughly 21°C to 24°C (70°F to 75°F) until seeds sprout in 2 to 3 weeks.
Thin to one plant per hole once the seedlings are established. When plants are 5-6cm (2 to 2 1/2 in) tall, transplant into the garden. Harden off seedlings first by gradually introducing them to cooler outdoor conditions—around 16°C to 21°C (60°F to 70°F)—and brighter sunlight before transplanting.
Celeriac thrives in full sunlight, though partial shade is acceptable if daytime temperatures are consistently cool. It prefers moist, fertile soil with good organic matter content to encourage uniform root development, and consistent watering is essential throughout the season to prevent woody or hollow centers.
- Sun Requirements: Full sun or partial sun
- Water Requirements: Medium
- Soil Types and Properties: Deep, fertile, well-draining loamy soil with ample organic matter
- Soil pH: Around 6.0 to 7.0
- Pot Size for Container Growing: At least 30 cm (12 in) in diameter
Planting
- Best Time to Plant
- Climates with freezing winters: Start seeds indoors in late winter, transplant in spring.
- Climates with milder winters: Sow in early spring or autumn, avoiding extreme heat.
Note: Check gardening calendars for the best planting times in your location
- Spacing: 25–30 cm (10–12 in) between plants, with rows spaced about 45 cm (18 in) apart
- Seed Sowing Method: Sow seeds into seed trays or indoors in small pots before transplanting
- Seed Sowing Depth: About 0.5 cm (0.25 in) deep
- Time to Harvest: Approximately 14–28 weeks from seed planting
- Mature Height/Spread: Around 30–40 cm (12–16 in) tall, with a spread of about 25 cm (10 in)
- Grown From: Seeds
Care and Maintenance
- Watering Tips: Celeriac requires consistent soil moisture, so regular watering is essential, especially during warm or dry spells, ensuring the root zone is thoroughly soaked without waterlogging. Mulching around the base helps retain moisture and keep the top growth clean, reducing chances of disease.
- Fertilization: A balanced, slow-release fertilizer or well-aged compost can be incorporated (dug) into the soil at planting time. Side-dress with fertilizer every few weeks to support steady growth. Overfeeding should be avoided, as excessive nitrogen may lead to lush top growth at the expense of bulb development, leading to smaller, fibrous roots.
- Pruning: Celeriac generally requires minimal pruning. However, removing yellowed or damaged outer leaves helps maintain airflow, reducing the risk of fungal problems. Some gardeners trim the lower leaves to expose the developing bulb for easier cleaning and to encourage a more uniform shape, but this practice is not strictly necessary.
- Support: Typically, celeriac does not require staking since the bulb forms close to the soil surface. However, in areas with strong winds, loosely tying leaves together can prevent damage.
Growing Difficulty
- Moderate Difficulty
Growing Tips
- Maintain constant soil moisture, as irregular watering can cause splitting or hollow roots. Adding well-rotted manure or compost at planting time helps boost both fertility and water-holding capacity.
- Celeriac can be partially blanched by lightly hilling soil around the swollen base as it grows protect it from sunlight and help maintain a paler interior. Celeriac naturally has a brownish, rough exterior, but the inner flesh remains white or cream-colored regardless. This practice can may further ensure that any exposed portions of the root do not turn green or develop tougher skin.
Companion Plants
- Good companion plants include: Brassicas (such as cabbage), leeks, onions, and spinach
- Avoid planting near: Corn and potatoes, as they can compete heavily for soil nutrients and moisture
Common Pests and Diseases
- Pests: Aphids, slugs, snails, and carrot root flies
- Prevention and control: Encourage beneficial insects (like ladybugs) for aphid control; use organic slug baits or handpick slugs/snails. Fine mesh row covers can prevent carrot root fly infestation. Keep beds clean and remove plant debris to reduce hiding spots.
- Diseases: Celery leaf spot (Septoria), bacterial blight, and various fungal rots
- Prevention and control: Ensure good air circulation, avoid overhead watering, and rotate crops to prevent disease buildup. Remove and destroy infected foliage promptly. Maintaining healthy soil with compost and balanced fertilization can strengthen plants’ natural resistance to pathogens.
Harvesting
- Harvest Time: Celeriac is usually ready to harvest once the swollen base reaches about 7–10 cm (3–4 in) in diameter, typically in mid to late autumn. Many gardeners choose to leave it in the ground until after the first frost, as exposure to cooler temperatures enhances its sweetness and flavor—much like parsnips or carrots. Celeriac can safely remain in the soil for extended periods, continuing to develop taste with exposure to light frost. If you live where winters are severe, lift the roots before the ground freezes or mulch them with straw or leaves to protect the roots, permitting harvesting at any time during the winter months.
- Harvesting Tips: Carefully loosen the soil around each plant, taking care not to damage the bulb. Gently lift the celeriac by its base or use a garden fork to pry it free. Trim off the leaves and rinse away excess soil. Store harvested celeriac in a cool, humid location to prolong freshness.
- Storage: Once harvested, store celeriac in a cool, humid spot, such as a root cellar or the crisper drawer of a refrigerator, to maintain freshness for several weeks or even months—ideal for long-term use in winter dishes.
Propagation
- Produce New Plants From: Seeds
Culinary Uses
Celeriac, with its mildly sweet and nutty flavor, is a versatile root vegetable that can be enjoyed both raw and cooked. Its cream-colored interior lends itself to a variety of preparations, from crisp salads to rich, comforting soups. Below are some practical tips on how to prepare and serve celeriac in everyday meals.
Peeling and Preparing: Celeriac has a thick, knobby skin that should be removed before use. Cut off the top and bottom, then use a sharp knife or sturdy peeler to remove the rough exterior. Aim to remove just enough to reveal the smooth, cream-colored flesh underneath.
Like many root vegetables, celeriac can oxidize and turn brown if left exposed to air for too long. If you’re preparing it in advance—or working slowly—immerse peeled pieces in a bowl of cold water with a splash of lemon juice or vinegar.
Raw Uses
- Salads & Slaws: Grating or julienning celeriac into thin matchsticks is a classic French approach (céleri rémoulade). Toss it with a tangy dressing made from mustard, mayonnaise, or a simple vinaigrette to highlight its mild, nutty flavor and crunchy texture.
- Pairing Suggestions: Celeriac pairs well with apples, carrots, and other crisp produce. Add fresh herbs such as parsley or chives for an extra burst of flavor.
Cooking Methods
- Roasting: Celeriac can be roasted in cubes or wedges with oil, salt, and pepper until tender and golden, which brings out its inherent sweetness and gives it a caramelized crust. Cut peeled celeriac into cubes or wedges, drizzle with oil, and season with salt, pepper, and herbs (e.g., thyme, rosemary, or garlic). Roast at about 200°C (400°F) until tender and golden, generally 30–40 minutes depending on chunk size.
- Mashing & Puréeing: It is also delicious when boiled and mashed on its own or mixed with potato for a lighter alternative to traditional mashed potatoes. Boil or steam peeled chunks until fork-tender (typically 15–20 minutes), then mash or blend with butter, cream, or stock. For a lighter version of mashed potatoes, combine equal parts boiled celeriac and potato, season well, and finish with a pat of butter or drizzle of olive oil.
- Soups & Stews: In soups and stews, diced celeriac adds depth and a pleasant nutty quality; simply simmer it with other vegetables and seasonings for a hearty dish. Dice celeriac and add it to soups, casseroles, or stews. It holds up well in longer cooking times, developing a sweeter, richer taste.
- Tip: Use celeriac to replace some of the potato or carrot for a subtle celery-like flavor without overpowering the dish.
- Frying or Sautéing: Another option is to fry thinly sliced celeriac into crisp chips, or sauté matchsticks in butter until lightly browned for a simple side.
- Chips: Thinly slice celeriac, pat it dry, and shallow-fry or oven-bake for a crunchy snack or side dish.
- Sauté: Cut into matchsticks or cubes and cook in a hot pan with butter or oil until lightly browned, then season to taste.
Serving Suggestions
- Classic French “Céleri Rémoulade”: Combine julienned raw celeriac with a dressing of Dijon mustard, lemon juice, mayonnaise, salt, and pepper. This crisp, tangy slaw is a staple in French bistros.
- Roasted Medley: Combine celeriac chunks with carrots, parsnips, and onions, then roast until tender for a colorful winter side dish.
- Creamy Soup Base: Sauté onions and garlic, add cubed celeriac with a light stock, and simmer until soft. Purée until smooth and finish with cream or coconut milk for a velvety texture.
Celeriac is relatively low in calories, its natural sweetness and moderate starch make it a healthy alternative to more carbohydrate-dense tubers. Celeriac stores well and remains fresh in a cool, humid environment, making it an excellent ingredient to have on hand. With its subtle sweetness and earthy undertones, celeriac offers a refreshing change from more common root vegetables, whether it’s used in a hearty stew or a light salad.
In conclusion, growing celeriac can be a rewarding crop for gardeners seeking an unusual, flavorful root crop. With proper care, consistent moisture, and a long, cool growing season, celeriac will reward you with distinctively aromatic and nutritious bulbs that can elevate a range of culinary dishes.
References
- Explore Cornell – Home Gardening – Vegetable Growing Guides – Growing Guide – Celeriac. Cornell University. http://www.gardening.cornell.edu/homegardening/scene810e.html
- Kohlrabi | Diseases and Pests, Description, Uses, Propagation. (n.d.). https://plantvillage.psu.edu/topics/kohlrabi/infos
- Home Gardening Series – FSA6080, Celeriac. University of Arkansas Cooperative Extension Service, Agriculture and Natural Resources. https://www.uaex.uada.edu/publications/PDF/FSA-6080.pdf
- Celery and Celeriac, Crop Profile CCD-CP-92. University of Kentucky Extension Service, Center for Crop Diversification. https://publications.ca.uky.edu/sites/publications.ca.uky.edu/files/celery.pdf