Botanically speaking, the edible part of celeriac is a swollen stem. Hardier and more disease resistant than its relative, celery, it has a similar flavour and aroma. Recent introductions have been bred to produce less knobbly ‘bulbs’ which are easier to prepare in the kitchen.
Sow in pots in a propagator, at 15-18°C (59-65°F), in March or in a cold frame, sowing seeds thinly.
Germination can be erratic.
Ideally, grow on in a frost-free glasshouse or cold frame, although good results are possible on a bright windowsill.
Transfer single seedlings to individual small pots as soon as they can be handled. Maintain temperatures of 15-18°C (60-65°F), as excessive cold can lead to premature flowering (bolting).
Celeriac is a moisture-loving plant that needs fertile, organic rich, moisture retentive soil and prefers full sun. Keep the soil constantly moist – it should never be allowed to dry out. Water before the onset of drought; mulching helps, too. Keep the ground weed free.
As the plants mature, remove the outer leaves as they fall horizontal, to expose the crown and allow it to develop. Remove side shoots if they appear.
Troubleshooting Growing Problems
Celery leaf spot: Brown spots appear first on older leaves, spreading to younger leaves.
Remedy: Use treated seed and rotate crops.
Slugs and snails: These feed on the young seedlings and you’ll see the tell tale slime trail on the soil around your crop, as well as on the leaves.
Remedy: There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.
Celery leaf miner: Small larvae tunnel through the leaves, leaving brown blisters. Severe attacks check growth.
Remedy: Grow under horticultural fleece or mesh. Pinch out affected leaves; do not plant seedlings with affected leaves. Parsnips can also be affected.
Harvest from October to the following March.
Leave in the ground until required, and cover with a thick layer of bracken or straw during the cold winter months to prevent the ground from freezing.
Alternatively, lift mature roots and transplant in spare ground in early spring, so the ground is available for sowing in spring or store in potting compost in doors with the leaves twisted off.
beans, broccoli, brussels sprouts, cabbage, cauliflower, chinese cabbage, chives, garlic, kale, kohlrabi, nasturtium, tomatoes