7/28/2016
Growing Bigger-Than-Life Begonias
Bart Sneek
The entire seed begonia market continues to boom, especially in interspecific begonias. These standouts deliver huge vigor, color and lastability. For your landscaper customers, they’ll appreciate the new Megawatt series from PanAmerican Seed. It has non-stop flowers spring through fall, thrives in heat and humidity, and tolerates drier periods between waterings. Plus, its sturdy flower stems hold the flowers above the foliage for superior show in-ground and in large-size containers.
With the addition of Megawatt, you’re positioned to supply both your landscaper and garden center customers with a full, high-impact interspecific begonia lineup. BabyWing is fast to market and perfect for earliest sales. Ship and sell Megawatt containers next, then follow up with main-season baskets of Dragon Wing.
Germination
Stage 1—(10 to 12 days)—Use a well-drained, disease-free soilless medium (pH 5.4 to 6.0, EC 1.0 mS/cm). Sow one pelleted seed per cell in 288 or larger plug tray. Water thoroughly to completely dissolve the pellet, but do not cover at sowing.
Temperature
Nights: 62 to 67F (16 to 19C)
Days: 65 to 75F (18 to 24C)
Average Daily Temperature (ADT): 65 to 70F (18 to 21C)
Light is not required, but is beneficial for uniform germination. Keep the media moist (level 5) during germination; Megawatt is very sensitive to drying out during the early stages. Maintain 95% to 97% relative humidity until cotyledons emerge. A saturated media and high humidity is critical to germinate successfully.
Stage 2—The optimum temperature is 72 to 75F (22 to 25C). Light up to 2,500 f.c. (26,900 Lux). Continue to keep the media very wet (level 5). Do not stress plugs. Begin fertilization at 5 days out of germination chamber.
Stage 3—Temperature and light remain the same. Keep media moisture medium wet to medium (level 4 to 3). Do not allow the seedlings to wilt. Increase the fertilizer rate to 2 (100 to 175 ppm N) once a week as soon as the plugs have begun to root out. Apply a balanced ammonium and nitrate-form fertilizer as needed to encourage growth and balance the media pH.
Stage 4—Temperature can be decreased to 65 to 67F (18 to 19C). Increase light up to 5,000 f.c. (54,000 Lux). Moisture can be reduced to medium dry (level 3). Avoid excess humidity later in the plug production, as this will create disease conditions. Fertilizer is the same as Stage 3.
Growing on to finish
Megawatt is a facultative short-day plant. It flowers faster under short days (10 to 12 hours). All interspecific begonias are daylength sensitive—long days will delay flowering. Megawatt Green Leaf varieties are 2 to 3 weeks slower to flower in long days. Megawatt Bronze Leaf varieties are less daylength sensitive than others and long days will only delay flowering 4 to 7 days.
Megawatt Green Leaf varieties are more vigorous than Bronze Leaf varieties. They require slightly heavier growth regulator rates than Bronze Leaf varieties.
Apply paclobutrazol spray for height control, especially for 6-in. (15-cm) or smaller containers. Spray rate can be up to 5 ppm, depending on environmental conditions, plant growing stage and varieties.
Start with paclobutrazol 2 to 3 ppm (0.5 to 0.75ml/l 0.4% formu-lation) spray about 2 weeks after transplant. If needed as plants grow bigger, apply higher rate of Bonzi 4 to 5 ppm (1.0 to 1.25 ml/l 0.4% formulation) two weeks later when grown under warmer or longer daylength conditions. No pinch needed.
Crop scheduling
Container Size:4.5-in. (12-cm) pot 1 Plant per Pot/Basket 7 to 8 Weeks from Transplant
Container Size: 6-in. (15-cm) pot 1 Plant per Pot/Basket 7 to 9 Weeks from Transplant
Container Size: 12-in (30-cm) pot 3 Plants per Pot/Basket 8 to 9 Weeks from Transplant
NOTE: Due to daylength sensitivity, when producing during summer with daylength 13 hours or longer, add 2 to 3 more weeks for Megawatt Green Leaf varieties.
GT
Bart Sneek is the Senior Global Product Manager for the EU Region of PanAmerican Seed. For more production and culture details, visit www.panamseed.com.