How to grow Celeriac

Apium graveolens · celery root, knob celery

A form of celery grown for its swollen, knobbly base, eaten as a root vegetable. It needs a long season, at least six months from sowing, and steady moisture.

Quick facts

Type	Vegetable
Family	Apiaceae
Light	Full sun
Soil pH	6–6.8
Frost	does not tolerate frost
Soil for sowing	from 10 °C
Germination	21 days
Seedlings ready	56 days
Sowing to harvest	150 days
Where it grows	Greenhouse, Open ground

When to plant

Sow for seedlings about 11 weeks before planting out.

Plant out in open ground about a week after your last spring frost, once the soil is warm.

In an unheated greenhouse everything moves about three weeks earlier.

The first harvest comes about 150 days after the shoots appear.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Germination	every 2 days	21…24 °C	—
Seedlings	every 3 days	18…21 °C	balanced (NPK), 42 days into the stage
Growth	every 4 days	15…24 °C	nitrogen, 21 days into the stage
Harvest	every 5 days	—	—

Open ground

Stage	Watering	Temperature	Feeding
Germination	every 2 days	21…24 °C	—
Seedlings	every 3 days	18…21 °C	balanced (NPK), 42 days into the stage
Growth	every 4 days	15…24 °C	nitrogen, 21 days into the stage
Harvest	every 7 days	—	—

Growing notes

Light

Full sun or light shade.

Soil

Rich, moisture-retentive soil with plenty of compost or well-rotted manure, pH 6–6.8. Avoid ground that dries out quickly or becomes waterlogged.

Care

Sow indoors at 15 °C or more and keep seedlings above 10 °C, as cold makes them bolt later. Harden off and plant out after the last frost, 30 cm apart in rows 40–45 cm apart. Keep the soil moist all the time, mulch, and give a good soaking if it dries out. Side-dress with nitrogen 3–4 weeks after planting out. Remove side-shoots and outer leaves that flop down. Lift from mid-autumn; the roots can stay in the ground over winter, under a thick layer of straw in cold areas.

Pests and diseases of Celeriac

Sources

Figures checked against these sources.