How to Grow Celery
Apium graveolens
Celery needs full sun, rich, moisture-retentive soil, and consistent watering — it will not tolerate drying out. Sow indoors in March at 15–20°C; germination is slow (2–3 weeks). Prick out into modules and harden off before planting out in late May after the last frost. Space 23 cm apart in blocks for self-blanching types, or in trenches for trench celery. Feed fortnightly with liquid fertiliser and water copiously. Harvest self-blanching types from late summer; trench celery is hardier and can be lifted into winter.
When to Start
Sow indoors 10 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 15°C.
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Growth Stages
Approximate days from start
Care Essentials
- Liquid feed fortnightly. Needs rich, moist soil and consistent watering.
- Self-blanching types are easier but less hardy. Start indoors in March — needs warmth to germinate.
Companion Planting
Tomato, Broad Beans, Runner Beans
Growing Conditions
- Min. soil temperature
- 15°C+
- Germination temperature
- 15–21°C
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
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Spacing & Planting
| Plant spacing | 23 cm |
| Row spacing | 23 cm |
| Sow depth | 0 cm |
| Mature height | 45 cm |
| Mature spread | 25 cm |
Companion Planting
Grows well with
Celery and tomatoes are mutually beneficial neighbours: celery's pungent foliage — rich in phthalides and terpenes — repels aphids and whitefly that commonly attack tomatoes, while tomato's dense canopy provides partial shade that reduces celery bolting in warm spells.
▼Broad beans harbour Rhizobium bacteria in root nodules that fix atmospheric nitrogen into plant-available ammonium, directly enriching the soil around the nitrogen-hungry celery. Chop and drop bean stems at the end of the season to release stored nitrogen as they decompose.
▼Runner beans fix atmospheric nitrogen via Rhizobium root nodules, steadily releasing ammonium into the soil that feeds nitrogen-hungry celery over the season. Grow them on a trellis directly behind the celery row so the beans don't shade out the shorter crop.
▼Celery's aromatic phthalide compounds act as an olfactory mask, disrupting the host-location ability of cabbage white butterflies and reducing egg-laying on nearby brassicas. Interplant celery every third or fourth cabbage to create a distributed chemical barrier.
▼Celery and leeks share similar moisture requirements and grow to compatible heights, making efficient use of bed space without competing aggressively. Their combined volatile profiles — phthalides from celery and sulphur compounds from leeks — create a mixed scent that confuses a wider range of pests than either alone.
▼Onion's sulphur volatiles and celery's phthalide scent together create a layered aromatic barrier that confuses a broad range of leaf-feeding insects navigating by smell. Both crops also prefer consistent moisture and similar pH, so they thrive under the same watering regime.
▼Keep away from
Both celery and parsnip belong to the Apiaceae family and share the same fungal and bacterial pathogens — most notably celery leaf spot (Septoria apiicola) and Sclerotinia — which can spread readily between them. Maintain at least 60 cm separation and avoid planting one in soil where the other grew the previous season.
▼Celery and potatoes both draw heavily on potassium and phosphorus, creating direct root-zone competition that stunts both crops when grown in close proximity. Potatoes also produce allelopathic glycoalkaloids that leach into the surrounding soil and can suppress celery seedling establishment; keep them at least 50 cm apart.
▼Pests & Diseases
Pest Celery Leaf Miner
Identification: Brown blotchy mines within leaves where larvae tunnel between leaf surfaces, leaves become papery and brown
- Squash larvae within leaf mines by pressing between finger and thumb
- Remove and destroy badly affected leaves promptly
- Cover with fine mesh from planting to prevent adult flies laying eggs
- No effective chemical treatments once larvae are inside leaves
Pest Slugs and Snails
Identification: Irregular holes in stems and leaves, slime trails, seedlings eaten at ground level
- Beer traps
- Nematode biological control
- Evening hand-picking
- Copper barriers around beds
- Ferric phosphate slug pellets
Pest Carrot Fly
Identification: Rusty brown tunnels in stems near the base, wilting foliage, small creamy-white maggots
- Fine mesh barriers at least 60cm high around the crop
- Avoid bruising foliage which releases scent attracting flies
- Companion plant with strong-smelling alliums
- Limited options for home gardeners
Disease Celery Leaf Spot Septoria apiicola
Symptoms: Small brown spots with dark borders on leaves and stems, spots merge causing leaves to die back, can spread to stalks
Treatment: Remove and destroy affected leaves promptly, improve air circulation
Prevention: Use disease-free or treated seed, avoid overhead watering, rotate crops on a 3-year cycle
Disease Celery Heart Rot
Symptoms: Soft, slimy brown decay in the centre of the plant, foul smell, outer stalks may look healthy initially
Treatment: Remove and destroy affected plants immediately, do not compost
Prevention: Ensure good drainage, avoid damaging plants when weeding, do not earth up too tightly
Growing Conditions
| Min. soil temperature | 15°C |
| Germination temperature | 15–21°C |
| Base growth temperature | 5°C |
| Min. daylength to start | 10h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Celery?
- Plant Celery 23cm apart with 23cm between rows.
- When can I harvest Celery?
- Celery is ready to harvest approximately 100 days after transplanting.
- What grows well with Celery?
- Celery grows well with tomato, broad beans, runner beans.
- Is Celery frost hardy?
- Celery is classified as Half Hardy.
