Mention celeriac and most people will say: celery? And after all it is a form of celery, a turnip-rooted celery. The French name is ‘celeri-rave' which means ‘turnip-rooted celery' and similarly the botanical name is Apium graveolens var. rapaceum. As a form of celery this is grown in Europe and further east to Asia. All kinds of celery have a short stem at soil level that carries the leaf stalks, but in the case of celeriac this basal stem is greatly enlarged and the leaf stalks are small compared to standard celery. The turnip-like ‘root' is actually a swollen stem and is the storage organ to over-winter for flowering in the second year of growth under natural conditions.
Celeriac is not easy to grow, and offers a challenge for even experienced growers, just as celery itself can be a challenge too. In fact, the best idea might be to buy a couple of celeriac roots first to see if it appeals as a vegetable and if it does, then to try growing it. It is a versatile vegetable and it adds to the limited repertoire of winter vegetables.
The edible part of the celeriac is the crunchy core of the root. The outside tough skin is peeled or sliced off, or the soft core bored out. It has a refreshing celery flavour, sweet but more intense than celery - it has a hint of parsley - and it can be eaten raw sliced or grated in salads or cooked in stews, soups and casseroles. It is not eaten on its own as such but used to impart flavour, celeriac dip made with mayonnaise and mustard is an example. It is often used in conjunction with other root vegetables. It is a good source of potassium and Vitamin C with some fibre and lesser amounts of other vitamins. It tends to turn black when cut so use lemon juice or cook right away.
Site and soil
Like celery, this crop loves full sunshine and really rich, deep humusy soil. If you had a lot of compost or manure to use up, this is a crop for the job.
The seed is sown in late February or early March as for celery, that is, indoors in a greenhouse. The young seedlings are pricked out into small pots as soon as they are big enough to handle.
The young plants are grown on without check until planting out in late May. They need to be well spaced, at least 40 centimetres apart each way. Otherwise they will not make good size and this is often a disappointment.
Like celery, celeriac is a very heavy feeder and the feeding is no good without lots of water. It needs watering during any dry spell of more than a few days. If water goes short, the root make develop hollow inside.
The outer ring of leaves is removed in mid-summer to encourage the round ball to develop and any secondary buds should sliced off. A top dressing of compost can be applied at that time.
The ‘roots' are harvested in autumn and winter as needed. It stands quite well in the open, not being damaged except by hard frost, and it can be stored like turnips in a cool place.
Although generally trouble-free, boron deficiency can wreak havoc causing splits and browning in the core of the roots. If turnips have shown boron deficiency, it would be essential to apply a trace element solution.