Marigold Sunburst Cultural Information

Plug Production
Sowing/Media: Use a well-drained, disease-free, peat-based plug medium with a pH of 6.0 – 6.2 and soluble salts (EC) <0.75 mmhos (saturated paste). Cover seed completely with coarse vermiculite after sowing, but make sure to see ribs of plug trays after watering. Otherwise, roots will grow across the top, making it difficult to transplant singly.

Germination (Stages 1 and 2): Keep medium uniformly moist until seedlings are hooking above the vermiculite covering, then dry down the covering to control early stretch. Soil temperature should be 68 – 72°F. Keep light levels <1500 footcandles. Allow about 5 – 7 days to finish germination.

Stage 3: Soil temperature should be 65 – 68°F. Light levels can be up to 3000 footcandles. Dry down between waterings for best rooting and control of height. Feed every other watering with 100 – 150 ppm N from 15-5-15, 17-5-17, or 13-2-13. Keep media pH 6.0 – 6.5, no lower, and media EC <1.5 mmhos (saturated paste).

Stage 4: Soil temperature can be lowered to 60 – 62°F. Maintain light levels around 3000 footcandles. Dry down between waterings. Feed every other watering with 100 – 150 ppm N from 13-2-13 to tone seedlings.

Plant Growth Regulators: Use sprays of B-Nine (1500 – 2500 ppm), A-Rest (3 – 10 ppm), Bonzi (10 – 20 ppm), or Sumagic (2 – 7 ppm) as needed. For best control of early stretch, use a sprench of A-Rest (3 – 5 ppm), Bonzi (2 – 5 ppm), or Sumagic (1 – 3 ppm) as seedlings are starting to hook above vermiculite covering. Do your own trial to avoid overdosing, as vigor of varieties, weather conditions, and cultural practices directly affect how much growth regulators to use.

Crop Time: 3 – 4 weeks for 512 plugs, 4 – 5 weeks for 288 plugs. Do not hold plugs, as buds formed in plug trays will prevent branching after transplanting.

Common Problems: Bronzing or speckling on lower leaves – low media pH (<6.0), purple lower leaves – too cool temps or too low phosphorus (P), buds forming too quickly – see above.

Growing on to finish
Container Size: Cell packs to 4-inch pots

Media: Transplant into a well-drained, disease-free, peat-based growing mix with media pH 6.0 – 6.2, no lower, and a media EC <1.5 mmhos (saturated paste).

Temperatures: Keep soil temperature 65 – 68°F for rooting out after transplanting, then lower to 62 – 65°F for growing on.

Light: Keep light levels 3000 – 5000 footcandles.

Irrigation and Fertilization: Practice a good wet/dry moisture cycle. Feed 1 – 2x/week with 150 – 200 ppm N from 15-5-15, 17-5-17, or 13-2-13. Keep media pH 6.0 – 6.5, and media EC 1.25 – 1.75 mmhos (saturated paste). If plugs have buds before transplanting, push growth with more NH4 feed, such as 20-10-20, but watch out for lowering media pH too much.

Plant Growth Regulators: Use sprays of B-Nine (2500 – 5000 ppm), Bonzi (15 – 30 ppm), or Sumagic (5 – 10 ppm) as needed. Drench with Bonzi (2 – 5 ppm) or Sumagic (1 – 2 ppm) when plants are up to size and flowering. Adjust rates and frequency of application based on vigor of varieties, weather conditions, and cultural practices. Do you own trials, especially with drenches, to avoid overdosing.

Common Problems: Leafspots (bacterial and Alternaria), bronzing or speckling on lower leaves – low media pH (<6.0), early flowering but poor vegetative growth – budding too early in plugs (either trim off flower buds or push with 20-10-20).

Crop Time: 4 – 6 weeks, depending on plug and container size, temperature, and light levels.jurisdiction of the English courts. Those who choose to access and use this information from outside the United Kingdom are responsible for compliance with local laws if and to the extent local laws are applicable.