Celeriac
Celery Root, Turnip-Rooted Celery, Knob Celery, Celeriac, Celery-Root, Root Celery, Turnip-Root Celery
Requires a very long season — start indoors 10–12 weeks before last frost. Grows the swollen root base, not celery stalks. Remove lateral roots and lower leaves as the root develops to encourage a smooth, round bulb. Consistent moisture is essential — drought causes cracking. Can be left in ground until heavy frost, improving flavor with cold. Very slow to germinate.
- Germination
- 10–21 days
- Soil temperature
- 16–21 °C
- Harvest after planting
- 100–120 days
- Spacing
- 30–35 cm
When to plant celeriac
Start seeds indoors 10–12 weeks before your last spring frost, and plant out 1–3 weeks after it.
Dashed line: typical last spring frost in zone 7 (Apr 5). Zone dates are averages; most of the UK is zone 8–9, central Europe 6–7 and the Baltics and Scandinavia 4–6. In the app, Tomatograph uses your garden's own frost dates.
How to grow celeriac
- 1
Sow indoors
Celeriac needs a long season. Sow on the surface 10–12 weeks before the last frost; germination is slow, 10–21 days.
- 2
Plant out
Plant after frost danger has passed, when plants are 8–10 cm tall, about 30 cm apart. Don't bury the crown.
- 3
Water and tidy
Keep the soil constantly moist; dry spells split the root. As the root swells, remove side roots and lower leaves for a smoother bulb.
- 4
Harvest
Lift from 100–120 days after planting. It can stay in the ground until hard frost, which improves the flavour.
Growing conditions
Light
Full sun
Water
High water
Temperature
4–24 °C
Frost tolerance
Frost-hardy — tolerates frost
Days to maturity
110–140 days
Ideal soil pH
6.5–7
How Tomatograph watches your celeriac
Tomatograph checks your local forecast every morning and only speaks up when one of these applies to your garden.
- First frost within 14 daysReminder to mulch the roots before winter.
- 3 days at 35 °C or aboveHeat-wave alert while plants are flowering or fruiting: shade and water early.
- Humidity above 80% for 48 hoursCheck for leaf spot, which thrives in those conditions.
- Under 5 mm of rain forecast over 3 daysWatering reminder: water deeply at the base, early in the morning.
- Within a week of maturityHarvest-window reminder based on when you planted.
Celeriac questions
- When should I plant celeriac?
- Start seeds indoors 10–12 weeks before your last spring frost, and plant out 1–3 weeks after it.
- How long do celeriac seeds take to germinate?
- Usually 10–21 days at a soil temperature of 16–21 °C.
- How long until I can harvest celeriac?
- About 100–120 days after planting out, depending on variety and weather.
- How far apart should I plant celeriac?
- Allow 30–35 cm between plants.
- What grows well with celeriac?
- Good neighbours include leek, onion, pea.
Growing guide written by Tomatograph. Planting figures from openplantdb (CC0 1.0). Zone frost dates are averages from openplantdb (CC0 1.0).