Start indoors 10 weeks before last frost. Soak seed for 24 hours, scatter seeds on soil mix and lightly cover with 1/8” of soil, as light is needed for germination along with a soil temperature of 21°C and constant moisture. Celeriac will take 7-14 days to germinate. When seedlings are approximately 1” tall, transplant into individual pots. Transplant outdoors after all risk of frost has passed, spacing about 6-9” apart in rows 24-32” apart.
Full sun is required. Celeriac is a heavy feeder and grows best in soil rich in organic matter with pH of 6.5. Before planting add plenty of compost and rotted manure. To conserve moisture and cut back on weeds, mulch around the plants and water during dry spells.
After the first few light frosts in the fall, loosen the soil around each plant with a garden fork and lift it free. Cut the tops an inch or two above the root and store in a cool dry location.