Why Grow Celeriac
It serves a useful purpose by providing that essential celery flavour in a root that can be stored through winter and early spring until the early celery crop becomes available. With a freezer already filled with berries, peppers, and other frozen delights, there’s little desire to add celery, making celeriac a practical choice. Additionally, Wellies and Waxjackets aims to grow some fresh celery over winter for salads.
Although the edible part of celeriac resembles a rounded root, it is, in fact, a swollen stem with a mild celery flavour. This versatile vegetable can be grated raw into winter salads, cooked and mashed like potatoes, added to stews and soups, or sliced and roasted. Rich in nutrients, antioxidants, and fibre, celeriac is said to be beneficial for digestion, bones, and heart health.
- Sow: Early March
- Time to maturity: 6-7 months
- Module sow: 1 seedling, pricked out, surface sown with light
- Spacing: 12-14" apart
- Frost tolerance: Young plants are not frost tolerant, but mature roots can withstand light frosts
- Watering: 1" weekly during dry spells
- Plant: In full sun or partial shade
How Many to Grow?
Celeriac is easy to grow, so the quantity depends on personal preference. However, it is essential to keep in mind that it requires considerable space for a crop that offers relatively low value.
When to Sow Celeriac
Celeriac requires a long growing season, so Wellies and Waxjackets sows the tiny seeds in early March. No early crops or additional successions are needed, as celeriac stores well and fresh celery can serve as a good alternative. Seedlings must be kept above freezing, so it’s advisable to avoid early sowing unless they can be kept indoors. They are typically kept alongside the peppers.
How to Sow Celeriac
Celeriac needs light to germinate, so it’s common to sprinkle the tiny seeds on the surface of a well-watered pot of compost, spray with water, and then cover with a propagator lid, a plastic bag, or a sheet of glass/plastic to retain moisture.
Tip: Wellies and Waxjackets has trialed surface sowing with a light covering of 1-2mm of compost, finding that the covered seedlings were stronger and germinated just as well.
The seeds should be placed in a warm area with access to light, sprouting within about two weeks. The covering should be removed as soon as seedlings are visible.
How to Prick Out Celeriac
Given their small size, it’s best to wait until the seedlings are 3-4 weeks old and their leaves are large enough to handle gently. At this stage, individual seedlings should be pricked out into a 12-cell tray, where they can remain until all risk of frost has passed.
Keeping celeriac above freezing is crucial to prevent bolting in summer. Therefore, they can be kept on a bright, sunny windowsill, in a frost-free greenhouse, or brought indoors if there’s a risk of frost.
Where to Plant Celeriac
Celeriac is slow-growing and requires full sun or light shade, as well as rich, water-retentive soil for optimal growth. Without these conditions, the roots may be small and less likely to store well.
On sandy soil, a thick compost mulch is added, and planting is done in one of the sunnier spots.
How to Plant Celeriac
Initially, the plants are small and should be spaced about 15” apart to allow for proper root development. Closer spacing may result in smaller roots, and anything less than 12” may lead to disappointing yields.
It's advisable to wait until night temperatures reach around 10°C (50°F) in late May, rather than the last frost date (mid-May). The ground should be mulched with 1-1.5” of high-quality compost. A hole is then dibbed through the compost, about 1” deeper than the module depth.
Gently press the module into the hole, ensuring it is about 1” below the surface of the compost, and avoid filling in the hole or covering the stems, especially the crown of the plant. Water thoroughly at planting and continue to water once a week until the plants are established and growing well.
Protection and Management
If cold weather threatens after planting, covering the plants with fleece or Envirotect is recommended until the weather warms and the plants become well established.
Celeriac is grown in the pottager garden, as it can be an attractive crop when well managed, similar to celery. However, older leaves may yellow and should be removed to improve aesthetics.
Slugs can damage the roots, so maintaining clean, slug-free beds is important.
How to Water Celeriac
Celeriac requires consistently moist soil and should never dry out. However, its watering needs are slightly less than celery. On sandy soil, it typically requires about 10-20mm of water weekly unless there’s significant rainfall.
How and When to Harvest Celeriac
Celeriac roots begin to develop above ground from late summer through autumn, with the first harvest possible in October. They can remain in the ground until spring, although Wellies and Waxjackets experienced loss during the severe freeze of 2022. Harvesting is typically done in October to allow for subsequent crops like garlic.
The plants can be lifted easily from sandy soil, or the roots can be cut off and left in the ground to decompose and nourish the following crops.
How to Store Celeriac
To store, snap off or cut the leaves, leaving a bare root ball. The dry texture of celeriac allows it to store exceptionally well without shrivelling, much like beetroot.
As with beetroot, a few fibrous roots should be left on, and the celeriac can be placed in an open box or crate filled with slightly damp pine wood shavings, stored below 10°C, where it can tolerate some frost exposure. Wellies and Waxjackets typically stores theirs in a wooden shed alongside beetroot and onions.
How to Deal with Pests
The main pest problem has been slugs, although woodlice can also pose issues, albeit more challenging to manage.
After harvesting, all root crops are at risk of being nibbled by mice, so scattering a few mouse traps baited with dry cat food around the storage area is advisable.
What to Plant Before Celeriac
Celeriac is typically planted after salad onions.
What to Plant After Celeriac
Suitable follow-up crops include salad onions, garlic, or over-wintered bulbing onions.
What to Interplant with Celeriac
The generous spacing between celeriac plants allows for interplanting with salad onions.
Recommended Varieties
Wellies and Waxjackets primarily grows ‘Monarch,’ a smooth-skinned variety with succulent flesh.
Other recommended varieties include:
-
Giant Prague: An heirloom variety introduced in 1871, known for its vigorous growth and relatively smooth skin with a slightly flattened base.
-
Ibis: A fast-growing, smooth-skinned variety that is vigorous, disease-resistant, and stores well.
-
Brilliant: Features smooth skin and white flesh that does not discolour.
-
Prinz: Large with smooth skin, crisp white flesh, and a good flavour, resistant to leaf disease and bolting.
