Celery
Apium graveolens var. dulce
Also known as: Garden celery, Pascal celery, Apio, Sellerie
Quick facts
- Category
- leafy greens
- Difficulty
- advanced
- Days to harvest
- 120 to 150 days
- Harvest type
- single harvest then replant
- Spacing
- 25 cm between plants
Environment
- Temperature
- 7–24°C
- pH
- 6 to 7
- EC (hydroponic)
- 1.8 to 2.4 mS/cm
- Daily light
- 14 to 20 mol/m²/day
Climate and zones
- USDA zones
- 3 to 10 (winter low around -40°C or warmer)
- Frost tolerance
- frost hardy (handles regular frost)
- Season
- cool (spring and fall crops)
Viable growing environments:
- outdoor year-round (in zone)
- outdoor in growing season (annual)
- unheated greenhouse / hoop house
- heated greenhouse
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Celery works in:
- deep water culture (rafts)
- NFT channels
- media bed (ebb and flow)
- wicking bed
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (celery works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Perlite (Expanded volcanic glass) | neutral / inert | very low | low |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 2 | 1 | 1 | 1 |
| vegetative | 2 | 1 | 2 | 2 |
Companion-growing notes
- Heavy uptake of potassium, calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
- High transpiration. Reservoir level will need regular top-ups during fruiting or flowering.
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
A notoriously finicky hydroponic crop that rewards careful attention to moisture and temperature. NFT, DWC, or raft systems suit celery well because the constant water contact mimics its wetland origins. EC 1.5-2.5 mS/cm. pH 6.0-7.0. Temperature: 15–22°C (critical: celery bolts in heat above 25°C and produces bitter, tough stalks; below 10°C for extended periods can also trigger bolting). Moderate light (DLI 12-18 mol/m2/day). Long crop: 80-100 days from transplant. Start seeds indoors 10-12 weeks before transplant (germination is slow, 2-3 weeks). The stalks must grow quickly and continuously to be tender and mild; any check in growth (drought, heat, cold, nutrient deficiency) causes bitterness, stringiness, and hollow stalks. Blanching (wrapping the lower stalks in cardboard or growing in opaque tubes) reduces bitterness and produces paler stalks, but self-blanching varieties ('Golden Spartan', 'Tango') eliminate this step. Calcium and boron supplementation prevents blackheart (internal browning of the growing point). For hydroponic growers, celery is most practical as a fall/winter crop where cool temperatures are naturally available.
Verified against: cornell-cea, u-florida-ifas, rhs-uk. Last reviewed 2026-05-15.