Greenhouse

• Hand remove all weeds prior to seeding.
• Do not apply herbicide in greenhouse!
• Remove any debris that may house insects (plants, soil, or bark).
• Avoid storing plants or food products near greenhouses to avoid insect and rodent movement to seedlings.

Trays

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

Mower

Thoroughly rinse with at least 10% household bleach solution for at least one minute prior to each clipping and when transitioning between greenhouses.

• Analyze water to monitor pH, bicarbonates, and trace elements. Sample with a well-rinsed 16-fl.oz drink bottle. Run water source several minutes before sampling. Sample results can indicate when to reduce excessive bicarbonate concentration with sulfuric acid.

• Optimum daytime: 86°F
• Optimum nighttime: 68°F
• Fluctuate temperatures between day and night to break seed dormancy.
• Reduce nighttime temperature to 55°F–60°F after stand establishment (14–20 days after seeding).
• Seed trays when five-day forecast predicts bright, sunny days.
• Cold-injured seedlings (Figure 1) will recover with addition of warm air.

Figure 1. Cold injury.

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Figure 1. Cold injury.

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

• Add 100–150 ppm 7 to 10 days AFTER seeding. This will reduce soluble salts injury potential and spiral root frequency (Figure 2).
• Add an additional 100–125 ppm four weeks after seeding. Total N for seedling production = 250 ppm.
• Maintain 125 ppm N if using an injector.

Figure 2. Spiral root and salt injury.

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Figure 2. 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 3) is rare when recommended fertilizers are used.

Figure 3. P deficiency.

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Figure 3. P deficiency.

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• Sufficient Ca should be included in commercial growing media and float bed source water.
• Add 5 oz gypsum/100 gal of float water prior to seeding if Ca is a limiting factor.
• For deficiency (Figure 4), 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 4. Ca deficiency.

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Figure 4. Ca deficiency.

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

• Use fertilizer with 0.02% B to ensure a 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 5)! Add total source water B concentration to fertilizer B to determine total B concentration in the float bed. Collect a diagnostic float water sample after fertilizer addition to analyze B concentration.

Figure 5. B toxicity.

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Figure 5. B toxicity.

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Gallons of Water in a Floatbed

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

Fertilizer Application

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

• Sanitize and ventilate the greenhouse 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 (Figure 6) and Rhizoctonia diseases.
• Store trays in a cool, dry, enclosed area when not in use.

Pythium Root Rot: Terramaster^® 4EC

• Preventative rate = 1.4 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 shedding is expected. Apply within eight weeks after seeding at three-week intervals for sequential applications. Maximum use of Terramaster is 3.8 fl. oz/season.

Target Spot (Figure 7): Quadris^® Flowable

• 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 (Figure 8)/Tobacco Mosaic Virus/Collar Rot (Figure 9) / Bacterial Soft Rot:

• No chemical control is available or recommended; discard infected trays and seedlings.

Figure 6. Pythium affected roots

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Figure 6. Pythium affected roots

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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 plants 1.5 inches above bud when plants are 2–2.5 inches above tray.
• Clipping five times improves viability by increasing stem diameter and reducing stem elongation. After the fifth clipping, seedlings are only being “held” until transplanting.
• Discard plant clippings at least 100 yards from greenhouse for sanitation.

Aphid, Flea Beetle, or Caterpillar Management in the Greenhouse:

• Orthene^® 97 = 0.375 oz in 3 gal of water/1,000 square feet during seedling production.
• Multiple formulations; always check the label.

Aphid, Flea Beetle, or Thrips Management in Greenhouse within Five Days Before Transplanting for Field Protection:

• Imidacloprid (Admire^® Pro) = 0.6–1.2 fl. oz/1,000. Transplant within five days of treatment, check label for further field protection.
• Thiamethoxam (Platinum^® 75 SG) = 0.17–0.43 oz/1,000 plants. Transplant within two days of treatment. Apply Admire^® Pro and Platinum^® overtop of seedlings and rinse thoroughly and immediately to ensure media wash-in.
• These materials can also provide control of soil insects such as wireworms at the high rates.
• Refer to the North Carolina Agricultural Chemicals Manual for soil insect control recommendations.

*Correcting bicarbonates with acid will elevate EC reading.

*Many greenhouse fertilizer labels contain estimated EC readings.