Gerberas

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Scientific Name: Gerbera jamesonii

Common Name: Transvaal, Barberton, or Gerbera daisy

'I. Botany/History'

  • Family: Asteraceae (Same family as Cosmos, Dahlia, Aster)
  • Growth Habit: A mature plant will vary according to where/how it has been planted. For most Gerberas the mature leaves will resemble those of a large dandelion. Measuring as much as two feet across showy flowers will originate from the center of the plant with a long peduncle.
  • Origin: South Africa
  • Development: Discovered by Robert Jameson in 1878. Around 1890 Richard Irwin Lynch worked on breeding Gerberas which lead to improvements from crosses with other genuses of the species. Around 1920 the flowers came to North America but not until the University of California at Davis proceeded with extensive breeding programs were the daisies actually suitable for the American garden.
  • Key people: Robert Jameson


'II. Uses'

  • Pots
  • Cut flowers
  • Bedding plants


'III. Propagation'

  • Sexual: Seeds are usually sown directly into flats or plugs. Flats are more labor intensive in the long run as plugs off one seed per pot.
  • Asexual: Micropropagation has found to be useful in cultivars which carry highly desirable characteristics such as elongated peduncles, larger flowers, and hardier plants but is not a widely used propagation method with Gerberas.


'IV. Growing/Flowering'

  • Light - (photosynthesis, photoperiodic responses): Gerberas require a lot of light for good flower production. Most production is focused in spring and summer when intensity is at its highest. Gerberas have shown to respond to short days with a slightly faster flower production while conversely long days delay flowering. Growers have had success extending the growing period for about four weeks between October and March. Any longer than four weeks has resulted in excessive foliage growth. Also during transplants from pot to pot and seedling stages HID light can be supplemented for at least 14 hours a day. Upon germination full sunlight should be shaded by 30-40%. Upon the existence of two or more mature leaves this restriction should be lifted.
  • Temperature: (recommended/necessary for different growth stages or growth regulation): During germination temperatures should be held between 73-75 degrees. Once complete germination has occurred with at least two mature leaves, night temperatures should be backed off to 68-72 degrees.
  • Water: With their vigorous nutritional requirements thorough waterings are important. After a thorough watering the plants should be allowed to dry down. This is to discourage soil born diseases. Wilting is very seriously with Gerberas as it is hard to reverse the shorter flower peduncles which can be hidden in the foliage. Early day watering is highly desirable as it allows the plant to dry down before the cool night temperatures which could inhibit disease and pathogen growth.
  • Nutrition: If a starter charge was added to the media before mixing do not begin application of fertilizer until roots reach the sides and bottom of the pot. A balanced fertilizer like 15-16-17(peat-lite special) or a 15-15-18 on a constant liquid fertilization basis Young plants should be fertilized with 100-150ppm for the first 2-3 weeks at which point the nitrogen ppm should be increased to 150-200. Along with the nitrogen, phosphorus should range between 6-50ppm, potassium 50-200ppm, calcium 40-250ppm, magnesium 25-200ppm. Please note though, excessive nitrogen can cause the foliage to overgrow which can cause hidden the flower stalks. Slow release fertilizer such as Osmocote (14-14-14) can be applied to media before mixing to be used in combination with a lower liquid fertilizer. Soil test should be taken to assure soluble salts are between 1.2 and 1.5mmhos/cm for proper nutrient uptake.
  • Media/Potting/Planting: Gerberas prefer a media with a high percentage of organic matter that is loose and well drained. What this translates to is 50-80% peat with perlite, vermiculite, calcine-clay, and course sand making up the remaining 20-50%.
  • Atmosphere: Gerberas flourish under warm temperatures and high humidity. This explains why most of the production occurs in Florida, Texas, North Carolina and California.
  • Growth Regulation (chemical, environmental, etc.): B-Nine is commonly used to keep Gerberas size under control. Most applications are made 10-14 days after potting into the final container at 2500ppm. B-nine can also be applied at the plug stage with 1000-1500ppm when there are at least 4 mature leaves present. B-Nine should never be applied anytime before four weeks when flowers are expected to open. It can adversely affect the size and shape.


'V. Special Considerations'(special timing or growing techniques, idiosyncraces, etc.): After 4-6 weeks of pot-to-pot spacing gerberas should be spaced out to allow for CO2 uptake. Tight spacing can delay flowering and cause leaves to stretch.


'VI Disorders'

  • Insect: Leaf miners, cyclamen mites, whiteflies, aphids, and thrips will take advantage of the Gerbera’s lush foliage.
  • Disease: Powdery mildew, Phytophthora (root/crown rot), Botrytis, impatient necrotic spot virus, and bacterial blight represent the main disease problems encountered by Gerberas.
  • Physiological: Foliage too large or flower stems too long caused from; low light intensity, Ammonium fertilizer too high, growth retardant too low. Short flower stems can be caused from plants too dry, soluble salts too high, glowing temperature too cold, or too much/late growth retardant. Flowers distortion caused fro, cyclamen mite or thrip problem, temperature too high or low, or soluble salts too high. Stunted plants or ones that are failing to grow can be caused from poor drainage or aeration, excessive heat in soil, excessive growth retartdant, or plants planted too deep. If plants are wilted or dying they could be planted too deep or root rot could have set in.


'VII. Marketing and Grading'

  • Marketing: No real specific holidays associated with gebera daisies.
  • Grading: Select sturdy, shapely plant with healthy foliage and bright, clear colored flowers. New flower buds desirable. Check leaf axils for insects. Avoid plants with disease or insect damage.


VIII. Postharvest Handling

  • Postharvest: Cut and pot gerbera daisies both havested when two outer rows of disc florets have opened and you can visually see the pollen. Stems are to be pulled not cut. They are slightly sensetive to ethylene.


IX. Cultivars

'Double Parade Mix', 'Happipot', 'Mardi Gras', 'Rainbow', and many others


X. References

http://www.ag.auburn.edu/hort/landscape/Gdaisy.htm

http://www.aces.edu/pubs/docs/A/ANR-1144/

http://aggie-horticulture.tamu.edu/floriculture/Hort429/lecture/gerbera.pdf

http://www.gerbera.org