Greenhouse

• Hand remove all weeds prior to seeding.
• Remove any debris that may house insects.
• Do not apply herbicide in greenhouse!

Trays

• Thoroughly remove all soilless media and plant debris.
• Steam at 176°F for 30 minutes.

Mower

• Thoroughly rinse with 50% household bleach solution prior to each clipping and when transitioning between greenhouses.

• Analyze water to monitor pH, bicarbonates, and trace elements. Sample with a well-rinsed 16-oz drink bottle. Run water several minutes before sampling. Sampling can indicate when to reduce excessive bicarbonate concentration (Figure 1).

Figure 1. Excessive bicarbonate.

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Figure 1. Excessive bicarbonate.

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• Optimum daytime: 86°F
• Optimum nighttime: 68°F
• Fluctuate temperatures to break seed dormancy.
• Reduce nighttime temperature to 55°-60°F after stand establishment (14-20 days after seeding).
• Seed trays when five-day forecast predicts bright, sunny days.
• Cold-injured seedlings (Figure 2) will recover with addition of warm air.

Figure 2. Cold injury.

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Figure 2. Cold injury.

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• Use 2-1-2 or 3-1-3 ratio fertilizers (for example, 20-10-20 and 16-5-16).

• Add 100-150 ppm 7 to 10 days AFTER seeding. This will reduce soluble salts injury to seedlings and can reduce spiral roots (Figure 3A and Figure 3B).
• Add an additional 100-125 ppm four weeks after seeding.
• Maintain 125 ppm N if using an injector.

Figure 3A. Spiral root and salt injury.

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Figure 3A. Spiral root and salt injury.

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Figure 3B. Spiral root and salt injury.

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Figure 3B. Spiral root and salt injury.

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• 2-1-2 or 3-1-3 ratio fertilizers provide sufficient P and K when targeted N rate is achieved.
• Excessive P can cause leggy or spindly transplants.
• P deficiency (Figure 4) is rare when recommended fertilizers are used.

Figure 4. P deficiency.

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Figure 4. P deficiency.

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• Sufficient Ca should be included in commercial media; if not, add 5 oz gypsum/100 gal of float water prior to seeding.
• For deficiency (Figure 5), apply 3.51 oz of calcium nitrate/100 gal of water overhead or to float water. Either will provide 50 ppm Ca and 40 ppm N.

Figure 5. Ca deficiency.

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Figure 5. Ca deficiency.

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• Use standard fertilizers to supply sufficient Mg and S. For deficiency, add Epsom salts at a rate of 4 oz/100 gal of float water.

• Use fertilizer with 0.02% B to ensure trace amount of B. Float bed concentration should be 1-2 ppm; less than 0.5 ppm is considered low. To correct, add no more than 0.2 oz Borax/100 gal of float water (this will supply 1.5 ppm B). Collect a water sample prior to seeding to determine B levels. Remember B is toxic to plants when concentration exceeds 2 ppm (Figure 6)! Add total source water B content to fertilizer B to determine total B concentration in float bed. Collect a diagnostic float water sample after fertilizer addition to analyze B concentration.

Figure 6. B toxicity.

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Figure 6. B toxicity.

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• Length (ft) × width (ft) × depth (ft) × 7.48 gal/cubic foot = gal of water/bed.

• Desired ppm of nutrient ÷ (% concentration in fertilizer × 0.75) = oz of fertilizer/100 gal.

• Sanitize and ventilate to control disease.
• Dispose of old and diseased trays. Steam-sanitize trays (176°F for 30 min) between each use to prevent Pythium root rot and Rhizoctonia diseases.
• Pythium Root Rot: Terramaster 4EC
  • Preventative rate = 1.0 fl. oz/100 gal of float water.
  • Curative rate = 1.4 fl. oz/100 gal of float water.
  • Mix Terramaster well throughout float bed. Root pruning is expected. Apply 3-8 weeks after seeding. Maximum use of Terramaster is 3.8 fl. oz/season.
• Target Spot (Figure 7): Quadris F
  • 0.14 fl. oz/1,000 square feet. Use at least 5 gal of water/1,000 square feet. Coverage is critical! Apply only once prior to transplanting.
• Black Root Rot/Tobacco Mosaic Virus/Collar Rot (Figure 8 and Figure 9):
  • No chemical control exists; discard infected trays and seedlings.

Figure 7. Target spot.

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Figure 7. Target spot.

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Figure 8. Black root rot.

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Figure 8. Black root rot.

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Figure 9. Collar rot.

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Figure 9. Collar rot.

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• Clip properly to ensure plant uniformity, hardiness, and maximum usable seedlings.
• Clip when plants are 2-2.5 inches above tray or 1.5 inches above bud.
• Clipping 5 times improves viability by increasing stem diameter and reducing stem elongation. After fifth clipping, seedlings are only being “held” until transplanting.
• Discard plant clippings at least 100 yards from greenhouse for sanitation.

For aphid, flea beetle, or caterpillar management in greenhouse:

• Orthene = 0.375 oz in 3 gal of water/1,000 square feet during seedling production.
• Bt materials are another caterpillar control option.

For aphid, flea beetle, or thrips management in greenhouse within 5 days of transplanting or for field protection:

• Imidacloprid (Admire Pro and others) = 0.6-0.8 fl. oz/1,000 plants (check formulation) for field protection.
• Thiamethoxam (Platinum SC and others) = 0.8 fl. oz/1,000 plants (check formulation) for field protection.
• Apply Admire Pro and Platinum overtop of transplants and rinse immediately to ensure media wash-in.
• These materials can also provide control of soil insects such as wireworms at higher rates. Refer to the North Carolina Agricultural Chemicals Manual for soil insect control recommendations.