Sow between mid-March and early April in seed trays, modules or pots of moist compost at 15°C (59°F). Sowing seed direct reduces transplant shock, but it is better to start in trays or pots and transfer modules as soon as the seedlings can be handled.
Sow seed thinly and apply the merest of covering of fine vermiculite or sieved compost. Patience is needed as germination takes time. Transplant the young seedlings when large enough to handle, which might not be until several true leaves appear. Plant single seedlings into 7.5cm (3in) pots or modules.
Low temperatures after germination can cause ‘bolting’ (running to seed) later in life; temperatures should not fall below 10°C (50°F) for long than 12 hours until they are established. Delay sowing until suitable temperatures can be maintained.
The key to success with celery is plenty of water throughout the growing season.
It is also liable to bolt or run to flower and seed if shocked or chilled during transplanting or growth. Make sure plants are properly ‘hardened off’ (acclimatised to outdoor conditions) before planting out at the end of May to early June.
Trenching celery: dig a trench 38-50cm (15-20in) wide and 30 cm (12in) deep in October/November or March, incorporating plenty of well rotted organic matter. Add 70g per sq m (2½oz per sq yard) of Growmore or other general purpose fertiliser. Plant in line along trench.
Plants can be then earthed up (mounding soil around the stems) so the stems become blanched, start doing this once stems are 30cm tall. Draw up the soil 7.5cm (3in) at a time until the top is exposed. Alternatively, use collars made of corrugated cardboard, brown paper, newspaper, plastic drainpipe or similar.
Other celery, including green and self-blanching celery: Plant 23cm (9in) apart in a block to ensure the plants shade each other to aid blanching.
Water regularly before the onset of dry weather – plants should never be allowed to dry out.
Self-blanching celery can be planted at ground level and will blanch itself by self-shading.
If growing celery in pots, feed every fortnight with a balanced liquid general fertiliser during the summer.
A light dressing of a high nitrogen fertiliser once they are established improves 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.
More info on Slugs and snails
Celery leaf spot: Brown spots appear first on older leaves, spreading to younger leaves.
Remedy: Use treated seed and rotate crops.
More info on Celery leaf spot
Plants are ready to harvest when large enough, between August and October, and before the first hard frosts. Cut them off at the base with a sharp knife. Trench celery might last into winter as late as December, but other celery will be harmed by November frosts.
A hearty roasted celery soup is great for the cold weather. Enjoy with a big chunk of crusty bread.
‘Giant Pink – Mammoth Pink’ AGM:A pink-tinged green variety, for harvesting from mid to late winter. Use as a trench celery.
‘Moonbeam’ AGM :Good long, dense, smooth stems. Use as a trench celery.
‘Octavius’ AGM:Attractive, short to medium-length, uniform crop, slightly ribbed, succulent stems. Use as a trench celery.
‘Celebrity’ AGM:Self-blanching, fairly short plants, with ribbed stems and good flavour.
‘Latham Self Blanching’ AGM:Vigorous with short ribbed stems and a good flavour. Reconfirmed after trial 2001.
Granada’ AGM - F1 hybrid:This self-blanching variety has pale green, reasonably smooth, quite fleshy stalks (petioles). Medium to strong flavour. Resistant to celery leaf spot (blight).
‘Ivory Tower’ AGM:Self-blanching; tall with smooth petioles and good flavour.