Celeriac

Apium graveolens (rapaceum variety) (Apiaceae or carrot family)

Production

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Soil preparation

• Celeriac should not follow other members of the carrot family, potatoes, cereals or cucurbits due to weed problems.
• Total nutrient uptake is 105 lbs. of N, 16 lbs. of P and 160 lbs. of K.
• Apply compost and other amendments based on the results of a soil test. Incorporate compost based on soil test results, and plant celeriac in raised beds.
• Spread lime as needed to increase both the pH and Ca levels. Dolomite lime will also increase Mg levels. Spread gypsum when calcium levels are low but pH is correct.
• A fertilizer company can add OMRI-listed potassium sulfate to compost if it doesn’t have enough K to meet the crop’s needs. If this isn’t possible, spread the correct amount of fertilizer and incorporate it before planting. Alternatively, you can side-dress it during cultivation. Divide the recommended rate of the soil test in half if side-dressing. 
• Test for boron and apply only as recommended by the soil test. A fertilizer company can add boron to compost to optimize boron distribution. If this isn't an option, distribute soluble boron through a water solution with a sprayer directly on the soil. If applied directly on the crop don't exceed more than 1 lb. of boron per acre to avoid leaf burn. 
• Most vegetable crops remove little P, but at times your soil test result will call for additional P. Unfortunately, there aren’t short-term options for an organic grower to increase the available P levels in the soil. Through the use of animal-based fertilizers, P will build up to a level in the soil that is sufficient for all vegetable crops.

Common recommended fertilizer rates¹

Nitrogen	Phosphorus	Potassium	pH
180	0-200	60-300	6.0-6.4
1Rates are for New York and are from Cornell University’s Nutrient Guidelines for Commercial Vegetable Production (2019). Check the Cornell website for updated guidelines, or consult with local experts for recommended rates outside New York.

Varieties

• Diamant, Brilliant

Seeding time and number of successions

• 1 planting only, 10–12 weeks before transplanting in the field.
• To avoid bolting, make sure the celeriac isn’t exposed to cold temperatures (45°) for more than 10 days. Keep the greenhouse at a minimum of 55°.

Greenhouse guidelines

• EZ Seeder seeding plate # 13

Cell pack tray	Germination temp	Growth temp	Hardening off	Notes
288	70°–75°	60°–70°	Reduce water Avoid low temps	Put plug trays on a wire mesh bench to encourage air pruning. Keep the greenhouse at a minimum nighttime temperature of 55°.

Transplant readiness indicators

• When the plants have at least 2 true leaves, transplant them to 72-, 98- or 128-cell trays.
  

Transplanting in 5- or 6-foot beds

Rows	In-row spacing	Planting depth (inches)	Notes
3	12 inches	Make sure the crown isn’t buried, since that will stop the plant from growing	Use a 12-inch sprocket or water wheel. Plant on your best ground.

Transplant tips

• As celeriac doesn’t provide a lot of shading, the crop tends to get weedy. You can transplant it in plastic mulch for better weed control. This also provides for much better water management.
• Harden plants off outside; plants that are lush don’t perform well in the field.

Cultivation procedures

• Use a basket weeder or wheel hoe when weeds are in the white thread stage. Weed control is more effective when you eliminate weeds before they emerge.
• Hand hoe between plants.
• For a second pass, use side knives only, or use a wheel hoe again. Hand hoe or hand weed again.
• Because celeriac doesn’t provide much shade and weeds will continue to be a problem throughout the season, keep the crop clean by frequently hand hoeing between plants.

Other cultural practices

• Celeriac is a finicky crop, as many organic growers experience difficulty supplying sufficient N and water to the crop during the growing season. You get the best results by side-dressing with an OMRI-listed fertilizer.
• Irrigate frequently for optimum yield and plant health. Frequency depends on soil type, evaporation, precipitation and the particular needs of the crop. 

Double cropping and/or cover cropping

• As celeriac is harvested in November, it’s often too late to establish a cover crop or follow it with another cash crop.

Harvest

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Ready-to-harvest and quality indicators

• Roots are 3–6 inches in diameter, and the timing is usually late in the fall.

Harvest procedures

• Wash hands and sanitize knives before harvesting.
• One crew cuts the celeriac out of the ground. Cut below the surface just enough to remove most of the soil and tangled roots, but not too high or the bulb will be damaged. If this is too difficult, first go through with a bed lifter to lift the celeriac out of the ground.
• The rest of the crew removes the tops and puts the roots in buckets.
• If harvesting for 1 delivery, empty buckets into boxes on a truck.
• If harvesting for bulk, move the crop from the buckets into a 20-bushel bulk bin. When buckets are full, drive a tractor with the bin down the driving lane and carefully dump the celeriac into the bin. The buckets are laid out over the full length of the bed so the entire crop from one bed is dumped into the bin at once. Leave the buckets at the same place to be used for the next bed.

Washing procedures

• Wash hands and rinse boots before entering the wash-and-pack shed, and cover up field clothes with a bib. If a long-sleeve shirt contains soil, remove this as well.
• Don't wash until it’s time for delivery. Then, put the celeriac through a barrel washer. This washer works best if filled up with approximately 300 lbs. of product. Alternatively use a brusher washer. Hose the celeriac before entering the washer, to soften any dirt on it.
• Do the sorting on the receiving end. A barrel washer should have a well-lit sorting table at the end.
• Sort the celeriac by size into regular boxes (about 15 large or 20 medium).

Additional resources

• Production Guide for Storage of Organic Fruits and Vegetables

Packing and storage summary for celeriac

Cleaning in the field	Remove dead and yellow leaves.
Packing in the field	35 lbs. per regular box or 800 lbs. per bulk bin
Packing for delivery	Use 20 lb. plastic bags whereby each root has a minimum diameter of 3 inches. See the International Federation for Produce Standards for the correct PLU code. Add the prefix 9 for organic crops. Pack in any clean box of choice for CSA distribution or the farmers market
Storage	At 32°–36° and 97–98% humidity. Pack in closed containers or bags for long-term storage.

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the Sustainable Agriculture Research and Education (SARE) program. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.