Introduction
Celeriac, also known as celery root, is a versatile and flavourful root vegetable that is becoming increasingly popular in UK gardens. Though it may look a bit gnarly, its creamy interior and distinct taste make it well worth the effort to grow. Celeriac thrives in cooler climates and, with the right care, can be a rewarding crop to harvest.
Why grow celeriac?
Celeriac is rich in vitamins C and K, as well as dietary fibre. Growing your own ensures that it’s fresh and chemical-free. Its long storage life means you can enjoy its unique flavour throughout the winter months, whether roasted, mashed, or added to soups and stews.
Suitability for different growing environments
Celeriac prefers a sunny spot in rich, moisture-retentive soil. It’s a relatively hardy plant that can withstand the cooler temperatures of the UK. However, it does require a long growing season, so it’s best suited for gardeners who can commit to regular watering and care.
Lifecycle
Celeriac is a biennial plant grown as an annual for its large, swollen root. Sown in early spring, it grows slowly throughout the summer and is harvested in late autumn. The plant forms a large, knobbly root that can be stored for several months after harvesting.
Sowing and harvesting periods
- Sowing: February to April (indoors), May to June (outdoors)
- Harvesting: October to December
Recommended varieties
Some well-regarded celeriac varieties for UK gardens include:
- ‘Monarch’
- ‘Prinz’
- ‘Alabaster’
How to sow
Celeriac seeds are tiny and need warmth to germinate. Sow them indoors from February to April in seed trays or modules, lightly covering the seeds with compost. Keep the trays in a warm spot, ideally at a temperature of 15-18°C (59-64°F). Seedlings can be transplanted outdoors once they have grown strong enough and the risk of frost has passed, usually around May or June.
How to prick out/pot on
When seedlings have grown their first true leaves, prick them out into individual pots or modules. This gives them more space to develop a strong root system. Keep them in a sunny, frost-free environment until they are ready to be planted out.
Where to plant
Choose a sunny location with rich, fertile, and moisture-retentive soil. Adding plenty of well-rotted manure or compost to the soil before planting will help to improve its structure and fertility. Celeriac needs consistent moisture, so it’s important to mulch around the plants to retain soil moisture and suppress weeds.
How many to plant (spacing)
Space celeriac plants about 30cm (12 inches) apart in rows that are 30-40cm (12-16 inches) apart. This gives the plants enough room to develop their large roots.
How to plant
Transplant celeriac seedlings to their final positions in late May to June, once all danger of frost has passed. Plant them at the same depth as they were in their pots, taking care not to bury the growing point, as this can stunt growth. Water them in well and keep the soil consistently moist throughout the growing season.
Protecting your plants
Celeriac is relatively hardy but can benefit from some protection against slugs and snails, especially when young. A mulch of straw or compost around the plants will help to retain moisture and suppress weeds, making it easier for the plants to thrive.
How to feed and water
Celeriac is a heavy feeder and will benefit from regular feeding with a balanced fertiliser. Keep the soil consistently moist, particularly during dry spells, as any check in growth can cause the roots to become tough and woody.
How to propagate, prune/manage while growing
Celeriac is grown from seed and doesn’t require pruning. However, as the plant grows, you can remove some of the outer leaves to expose the top of the root. This helps the root to swell and develop properly. Keeping the plants well-watered and weed-free will also encourage healthy growth.
How and when to harvest
Celeriac is ready to harvest from October onwards. The roots should be around the size of a large grapefruit and feel firm to the touch. To harvest, gently lift the roots out of the soil using a fork, taking care not to damage them. Brush off any excess soil and trim the leaves, leaving a short stalk.
How to store
Celeriac stores well in a cool, dark, and frost-free place. The roots can be kept for several months, making them a valuable crop for winter use. Alternatively, you can leave the roots in the ground and harvest as needed, as long as the soil isn’t frozen.
How to eat/cook
Celeriac’s mild, celery-like flavour makes it a versatile addition to many dishes. It can be roasted, mashed, grated into salads, or used in soups and stews. For a simple and delicious side dish, try roasting celeriac with olive oil, garlic, and herbs.
How to deal with pests and disease
Celeriac is generally hardy, but can be susceptible to pests like slugs and snails, particularly when the plants are young. Keep the area around the plants free of debris, and use organic slug pellets or barriers if necessary. Fungal diseases like celery leaf spot can affect celeriac, so it’s important to rotate crops and avoid growing celeriac or celery in the same spot more than once every three years.
When and how to remove the plants
After harvesting, remove any remaining plant debris from the soil and compost it. If you plan to grow celeriac in the same spot next year, add plenty of organic matter to the soil to replenish nutrients. Otherwise, prepare the soil for your next crop by digging in compost or well-rotted manure.
What to plant before and after
Celeriac benefits from being planted after legumes like peas and beans, which help to enrich the soil with nitrogen. It can also follow leafy crops like lettuce or spinach. After harvesting celeriac, consider planting a nitrogen-fixing crop like peas or beans, or a leafy green crop such as spinach or lettuce, to help replenish the soil.
What to interplant with
Celeriac can be interplanted with crops like onions, which can help to deter pests. It also pairs well with shallow-rooted herbs like parsley and coriander, which won’t compete with its deep root system. Avoid planting celeriac near other root vegetables to minimise competition for nutrients.