Celeriac, a member of the celery family, isn't grown for its stalks like other celeries. Instead, it is grown for its large, bulbous root that forms right at soil level. The root is grated or sliced and used in salads, soups and other dishes where regular celery is used. While it requires the same long growing period of celery to reach full maturity, celeriac can also be harvested earlier when the root is smaller if you have a short growing season. If your summers are too short for celery, then celeriac is a good substitute.
Fill individual seed pots with a quality potting soil. Fill the pots to within 1 inch of the rim and moisten the soil thoroughly.
Plant two to three seeds per pot directly on the soil surface. Cover with a 1/8 inch layer of soil, then mist the top of the soil with a spray bottle to moisten.
Cover the pot with a layer of plastic wrap and place in a 65 degrees F room to germinate. Germination takes 14 to 21 days.
Remove plastic once sprouts appear. Place the celeriac seedlings under grow lights or in a sunny window sill and keep the soil moist at all times.
Transplant celeriac outside on the last expected frost date in your area. Harden off seedlings one week before transplanting by placing them outside for two hours the first day, and gradually increasing the time each day for seven days.
Plant in a full sun, well draining garden bed. Space seedlings 6 inches apart in 18 inch wide rows. Harvest between 90 and 120 days after planting.