Cauliflower

Brassica oleracea (botrytis group) (Brassicaceae or cabbage family)

Production

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Soil preparation

• Don’t follow cauliflower after other cole crops.
• Total nutrient uptake is 165 lbs. of N, 10 lbs. of P and 208 lbs. of K.
• Plant early cauliflower after a cover crop of oats and field peas. 
• Summer-planted cauliflower does well when planted after a spring seeding of oats, forage peas and bell beans at a rate of 45 lbs. of oats, 100 lbs. of peas and 100 lbs. of bell beans per acre. This cover crop can supply all of cauliflower’s N needs. Mow before the oats start flowering to avoid oats reseeding. Alternatively, remove oats from the seeding mix for easier incorporation. 
• You can also plant fall cauliflower through a rolled and crimped cover crop of Austrian winter peas. Plant this cover crop in early September at a rate of 200 lbs. to ensure good weed control. In this case, take a soil test in the preceding year and fertilize as needed to provide enough nutrients for both the Austrian winter peas and the vegetable crop. Inoculate seed and reduce N application to enhance N uptake by N-fixing bacteria. To properly kill peas, use a no-till planter (without seed in the box) and slice the cover crop with the coulters of the drill. 
• Incorporate compost or a cover crop of oats and peas, and plant cauliflower in raised beds or on flat ground.
• Apply compost and other amendments based on the results of a soil test.
• 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.

Common recommended fertilizer rates¹

Nitrogen	Phosphorus	Potassium	pH
120	0-160	0-200	6.2-6.5
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

• New York variety trial

Varieties popular with organic growers are Panther (green), Quasar, Cassius and Skywalker

Greenhouse guidelines

• EZ Seeder seeding plate #1

Cell pack tray	Germination temp	Growth temp	Hardening off	Notes
72, 98 or 128	75°–90°	>60°	Reduce water	Put plug trays on a wire mesh bench to encourage air pruning. Take plants outside 1 week before planting in field.

Seeding time and number of successions

• For spring harvest, seed cauliflower in a greenhouse 5 weeks before you can transplant in the field. You can spread out the harvest with multiple plantings or by using varieties with different days to maturity.
• For fall harvest, choose multiple varieties with different days to maturity to stagger the harvest. Follow that with a few more plantings of the variety with the longest days to maturity to finish off the season. In the northern United States, fall-harvested cauliflower is seeded in late May through June, and it is transplanted in July.

Signs to watch for and what to do

• Watch that plant starts don’t start to get leggy from too much warmth; put them outside if you notice this happening.

Transplant readiness indicators

• Harden plants off outside; plants that are lush don’t perform well in the field.
• Transplants are ready when they pull out of their cells easily, and they should not be older than 5 weeks. Stunted plants don’t form large heads. Transplanting after 5 weeks can lead to plants being rootbound, which increases the risk of transplant shock.

Transplanting in 5- or 6-foot beds

Rows	In-row spacing	Planting depth (inches)	Notes
2	24 inches	As deep as possible	Use a 24-inch sprocket or water wheel. Water after planting.

Transplanting tips

• Adjust mechanical transplanters so there is good contact between the plug or root ball and the soil. Ensure plants are properly rooted before cultivation.
• Plant as deep as the plant allows without burying any leaves.

Cultivation procedures

• Ensure plants are properly rooted before cultivation. 
• Use sweeps (with torsions if possible) followed by a finger weeder 7–10 days after transplanting, or as soon as possible without damaging the plants. Alternatively, use a tine weeder; but this works better when you use bare root transplants because tine weeders tend to uproot plugs.
• Hand hoe in between plants as necessary.
• Use a finger weeder in combination with side knives for a second pass when new weeds emerge. Alternatively, if you want very slight hilling, use spring hoes in combination with side knives.
• If a third cultivation is necessary, use Lilliston rolling cultivators and hill aggressively without burying the plants.

Frost, insect and disease protection

• Control black rot (Xanthomonas) by purchasing clean seeds, keeping the greenhouse clean and exposing seed to hot water treatment. Some organic seed suppliers hot treat their seeds, so check with them before applying your own treatment, as double treatment can affect germination.
• Flea beetles
  • Cover the crop with floating row covers or insect netting after transplanting to avoid flea beetle damage. Keep covered until harvest. Alternatively, use a spinosyn-based product like Entrust. 
  • If possible, follow Extension bulletins that publish the timing of each generation of flea beetles, or place yellow sticky cards at plant height to monitor their presence. Check the cards at least twice a week.
  • Spray beneficial nematodes on heavily infected land to control flea beetle grubs and avoid future generations. Flea beetles tend to overwinter in nearby hedgerows and grass strips.
• You can prevent cutworms by spraying the soil with the beneficial nematode Steinernema carpocapsae. Once the pest is in the crop, control the population by spraying the crop with Bacillus thuringiensis kurstaki, or spread a baited product containing spinosyn, like Seduce, around the plants.
• Cabbage maggots: To reduce infestation of cabbage maggots on young seedlings, cover seedlings with floating row covers or insect netting as you would for flea beetles. Maggots appear in 3–4 generations in the Northeast, starting in early spring.
• Scout for the eggs of imported cabbage worms or diamondback moths on the underside of leaves. When the small worm population is more than per plant, spray a Bacillus thuringiensis (Bt aizawai or Bt kurstaki) product, such as XenTari, or a spinosyn-based product, such as Entrust, every week until the population is under control. Alternate your spraying schedule by using Bt products along with a spinosyn-based product to avoid resistance buildup.
• To avoid Alternaria leaf spot, plant far away or upwind from earlier-planted cole crops, and avoid overhead irrigation. Regular applications of Bacillus amyloliquefaciens, available as Double Nickel, have shown the best controls in research. Bacillus subtilis, available as Serenade, and mineral oil like JMS Stylet-Oil have shown some control for a few growers. Regular sprays with giant knotweed extract, such as Regalia, appear to reduce Alternaria as well by activating the plant’s natural defenses against fungal and bacterial diseases.
• Swede midge has become a problem for many growers over the past few years. As it is an invasive species, it has no native enemies. Exclusion through row covers and rotation more than ½ mile away from last year’s crop may provide effective protection.

Other cultural practices

• Irrigate frequently for optimum yield and plant health. Frequency depends on soil type, evaporation, precipitation and the particular needs of the crop. 
• As the cauliflower matures, cover the white part with the outer leaves to prevent the curds from yellowing. Inspect the crop 3 times a week and cover the emerging heads (the moment when the small white heads are just visible through the leaves) by cracking a few leaves and bending them over so the heads are no longer exposed to direct sunlight. By the time the leaves wither, the head should be at full size. Another method is to bundle the outer leaves with a large rubber band. Use a different color rubber band for each inspection day, which allows harvesters to know how long a plant has been covered.

Double cropping and/or cover cropping

• If possible, mow plants as low as possible with a flail mower. Incorporate crop residue with a disc, and plant a cover crop.
• If it’s too late to establish a cover crop, leave cauliflower plants in the field after harvest. Cauliflower plants are better at holding soil in place over the winter than a poorly established cover crop. Alternatively, you can overseed rye a few weeks before harvesting, but it needs to be done before the end of October. Be careful not to get seeds caught in the plants. Never broadcast rye after the curds have started to develop.

Additional resources

• Organic Production and IPM Guide for Cole Crops

Harvest, White and Green

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Ready-to-harvest and quality indicators

• Firm, white heads over 4 inches in diameter without any presence of worms.
• It’s too late to harvest once heads become loose and turn yellow.
• The heads need to be kept out of direct sunlight 1 week before harvest. To do this, fold several large leaves over the small white head or tie the leaves with a large rubber band. If using rubber bands, choose 3 different colors to represent 3 different harvesting days. Tying is done at the same time as harvest. (Many varieties now are “self blanching” and don’t require this step.)

Harvest and cleaning procedures

• Wash hands and sanitize knives before harvesting.
• Cut the stem just under the head, leaving some leaves attached.
• Cut off the tops of wrapper leaves surrounding the head. Do this so there is a complete circle of leaves surrounding the head. They will protect the outside of the head from bruising and will provide a nice appearance. Any bruises turn into brown spots in less than 6 hours.
• If harvested for a CSA or farmers’ market, layer 6 heads in the box and use cauliflower leaves or cardboard to separate them from the next layer. All heads are face up.
• For wholesale, use an appropriate container in the field, then sort and repack heads in a packing shed. Sort by size and pack 12–24 heads per box, with a 12-count box being most common.

Additional resources

• Wholesale Grading and Packing Instructions
• Postharvest Factsheet Cauliflower
• Production Guide for Storage of Organic Fruits and Vegetables 

Packing and storage summary for cauliflower

Cleaning in the field	Cut off tops of wrapper leaves.
Packing in the field	12–24 heads per box, with a 12-count being most common
Packing for delivery	9 or 12 in a single layer box. Many buyers require cauliflower to be wrapped in plastic jackets to reduce postharvest losses. For a CSA, most packing is done in the field to avoid damage from handling. See the International Federation for Produce Standards for the correct PLU code. Add the prefix 9 for organic crops.
Storage	At 32°–41° and 95–100% humidity. Pack in closed containers or wrap cauliflower heads in plastic bags for storage longer than 3 days. Cauliflower is sensitive to ethylene exposure. Allow for good air exchange and don’t store with crops that release ethylene.

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.