Advanced Kohlrabi Production: Commercial Systems & Intensive Management

This advanced guide addresses commercial-scale kohlrabi production, covering intensive management systems, precision irrigation, integrated pest and disease control, and post-harvest handling for market success. Whether you're scaling a market garden or developing specialty crop production, these strategies will optimize your kohlrabi enterprise.

Commercial Production Systems

Site Selection Criteria

Optimal Field Characteristics:

Factor	Specification	Importance
Soil Type	Loam to sandy loam	Critical for root development
Soil pH	6.0-7.0	Disease prevention
Drainage	Excellent	Prevents root diseases
Previous Crop	Non-brassica	3+ year rotation required
Slope	1-2%	Air drainage for frost protection
Wind Protection	Moderate	Reduces pest pressure

Soil Preparation Protocol:

Deep tillage (10-12") in fall
Soil test and amendment application
Cover crop incorporation if applicable
Final bed formation 2-3 weeks before planting
Plastic mulch installation (optional) for weed control

Commercial Planting Configurations

Bed System Options:

System	Bed Width	Rows/Bed	In-Row Spacing	Plants/100 ft
Standard	36"	2	6"	400
Intensive	42"	3	6"	600
Ultra-intensive	48"	4	4"	1,200

Transplant vs. Direct Seeding:

Method	Advantages	Disadvantages
Transplants	Uniform stands, precise timing	Higher cost ($15-25/tray)
Direct seeding	Lower cost, no transplant shock	Thinning required, less uniform
Precision seeding	Reduces thinning, lower cost	Equipment investment

Production Calendar (Northern Temperate)

Spring Production:

Week	Activity	Notes
-8	Start transplants (greenhouse)	200 cells/tray
-4	Harden transplants	Reduce water, increase ventilation
0	Field transplanting	After last hard frost
+3	First side-dress	Nitrogen application
+6-8	Harvest begins	50-55 day varieties

Fall Production (Premium Quality):

Week Before First Frost	Activity
12	Start transplants or direct seed
10	Transplant to field
7	Begin pest monitoring
4-6	Primary harvest
0-4	Protected harvest (row covers)

Precision Fertigation

Drip System Design

Specifications:

Component	Specification
Drip tape	8-mil, 8" emitter spacing
Flow rate	0.45 GPM/100 ft
Operating pressure	8-12 psi
Filtration	150-mesh screen
Injection	Venturi or electric dosatron

Fertigation Schedule

Weekly Nutrient Targets (lbs/acre):

Week	N	P₂O₅	K₂O	Ca	Notes
1-2	3	2	2	—	Establishment
3-4	6	1	4	2	Vegetative growth
5-6	8	1	5	3	Bulb development
7-8	4	0.5	3	2	Pre-harvest

Total Season Application:

Nitrogen: 50-70 lbs N/acre
Phosphorus: 30-50 lbs P₂O₅/acre
Potassium: 60-80 lbs K₂O/acre
Calcium: Critical for quality

Micronutrient Management

Critical Micronutrients:

Nutrient	Rate	Timing	Method
Boron	0.5-1 lb B/acre	Pre-plant + foliar	Granular + spray
Molybdenum	0.5 oz/acre	Transplanting	Transplant solution
Zinc	2-4 lb Zn/acre	If deficient	Foliar

Boron Deficiency Prevention:

Common issue in brassicas
Causes hollow stem, internal browning
Apply Solubor (0.5 lb/100 gal) as foliar spray at week 3 and 5

Integrated Pest Management

Monitoring Protocols

Scouting Schedule:

Twice weekly during active growth
Check 5 locations per acre, 5 plants per location
Record pest species, numbers, life stages
Note beneficial insect activity

Action Thresholds:

Pest	Threshold	Action
Imported cabbageworm	0.3 larvae/plant	Bt application
Diamondback moth	0.5 larvae/plant	Spinosad rotation
Cabbage aphid	10% plants infested	Targeted spray
Flea beetles	5% defoliation	Row covers or spray

Biological Control Program

Augmentative Release Schedule:

Beneficial	Target	Release Rate	Timing
Trichogramma spp.	Moth eggs	100,000/acre/week	Throughout season
Aphidius colemani	Aphids	0.5/sq ft weekly	When aphids detected
Beauveria bassiana	Multiple	Per label	Every 7-14 days

Chemical Control (When Necessary)

Rotation Program:

Week	Product Class	Active Ingredient	Target
1	Microbial	Bt var. kurstaki	Caterpillars
2	Spinosyn	Spinosad	All larvae
3	Microbial	Bt var. aizawai	Caterpillars
4	Pyrethroid	Lambda-cyhalothrin	Multiple

OMRI-Approved Options:

Target	Product	Rate	PHI
Caterpillars	Bt (Dipel)	0.5-2 lb/acre	0 days
Caterpillars	Spinosad (Entrust)	1.5-2 oz/acre	1 day
Aphids	Pyrethrin	Per label	0 days
Aphids	Neem oil	1-2%	0 days
Flea beetles	Kaolin clay	25-50 lb/acre	0 days

Disease Management

Clubroot Management Protocol:

Practice	Implementation
pH management	Maintain 7.0-7.2 with lime
Rotation	Minimum 7 years without brassicas
Clean transplants	Certified disease-free
Soil testing	PCR testing of soil before planting
Resistant varieties	Limited availability, use when possible

Black Rot Prevention:

Strategy	Details
Seed treatment	Hot water (122°F for 25 min) or Thiram
Transplant inspection	Reject any symptomatic trays
Irrigation	Avoid overhead; use drip
Tool sanitation	10% bleach between fields
Roguing	Remove infected plants immediately

Harvest and Post-Harvest Operations

Harvest Specifications

Commercial Grade Standards:

Grade	Size	Quality Criteria
Fancy	2.5-3.5"	Perfect shape, no defects
No. 1	2-4"	Minor blemishes acceptable
No. 2	1.5-4.5"	More defects, misshapen OK

Harvest Indicators:

Size reaches grade requirements
Flesh is firm, not spongy
Skin is smooth, not cracked
No hollow stem when cut

Harvest Procedures

Field Harvest Protocol:

Harvest in early morning (maximum turgidity)
Cut at soil line with sharp knife
Remove leaves immediately in field
Leave 1" stub on stem
Place in clean harvest bins
Move to shade within 30 minutes

Cooling and Storage

Cooling Methods:

Method	Time to Temperature	Best Application
Hydrocooling	15-20 minutes	High volume
Forced-air cooling	2-4 hours	Packed product
Room cooling	12-24 hours	Small quantities

Storage Specifications:

Parameter	Optimal	Notes
Temperature	32-34°F (0-1°C)	Critical for quality
Relative humidity	95-98%	Prevent wilting
Storage duration	2-3 months	Premium quality: 1 month
Ethylene sensitivity	Low	Can store near fruits
Freezing point	30.2°F (-1°C)	Avoid freezing

Packing and Presentation

Pack Formats:

Format	Count/Weight	Market
Bulk bin	40-50 lbs	Processing, wholesale
Consumer pack	2-3 bulbs (1 lb)	Retail
Bunched (with leaves)	2-3 bulbs	Farmers market
Mixed color pack	2 green + 2 purple	Premium retail

Quality Control:

Size uniformity within grade
No cracking or mechanical damage
Clean cut, minimal stem
Free of pest damage
Temperature verified (<40°F)

Economic Analysis

Production Costs (Per Acre)

Category	Cost Range
Land preparation	$200-400
Transplants (20,000/acre)	$600-1,000
Fertilizer	$150-300
Irrigation	$100-200
Pest management	$150-300
Labor (cultivation)	$300-500
Harvest labor	$800-1,200
Packing materials	$200-400
Total Variable	$2,500-4,300

Revenue Projections

Market Channel	Price	Units/Acre	Revenue
Wholesale	$0.75-1.25/lb	15,000-20,000 lbs	$11,250-25,000
Farmers Market	$2.00-3.00/lb	10,000-15,000 lbs	$20,000-45,000
Restaurant Direct	$1.50-2.50/lb	8,000-12,000 lbs	$12,000-30,000

Break-Even Analysis

Wholesale break-even: ~4,000 lbs @ $1.00/lb
Premium market break-even: ~2,000 lbs @ $2.50/lb
Purple varieties command 20-30% premium

Troubleshooting Advanced Issues

Problem: Hollow stem in commercial plantings

Cause: Boron deficiency, rapid growth, heat stress
Solution: Soil and tissue testing, boron application, variety selection

Problem: Variable sizing across field

Cause: Irrigation non-uniformity, soil variation, transplant quality
Solution: Audit irrigation system, zone management, transplant grading

Problem: Short shelf life

Cause: Field heat, delayed cooling, temperature fluctuations
Solution: Morning harvest, rapid cooling, cold chain maintenance

Problem: Unmarketable appearance despite good flavor

Cause: Flea beetle damage, weather checking, handling damage
Solution: Integrated pest management, row covers, harvest training

Quality Assurance Protocol

Pre-Harvest:

Scout for pests 48 hours before harvest
Check bulb size against grade targets
Verify cooling facility operational
Prepare clean harvest equipment

Harvest Day:

Begin harvest before 8 AM
Remove leaves in field
Transport to cooler within 1 hour
Begin cooling immediately

Post-Harvest:

Product at 34°F within 4 hours
Grade and pack within 24 hours
Document lot numbers for traceability
Maintain cold chain to customer

With these advanced production systems, you'll achieve the consistency, quality, and efficiency required for successful commercial kohlrabi production.