Propagation of Zonal Geranium Vegetative Cuttings in Terra Plugs

screen-shot-2016-09-21-at-11-06-24-amVijay Rapaka, Ph.D.
Corporate Grower Research & Technical Support Manager
Smithers-Oasis Company, Kent, Ohio, USA

Brenton Williams
Greenhouse Research Technician
Smithers-Oasis Company, Kent, Ohio, USA

The following is the general procedure for the Propagation of Geraniums in Terra Plugs:

  • Saturate the Terra Plugs and place them in a disinfected propagation area
  • Insert the cuttings on the same day they arrive, if the varieties are sensitive to senescence. Cuttings can be stored overnight at temperatures between 5° C to 10° C (40° F to 50° F) in the case of non-sensitive varieties
  • A rooting hormone is generally not required, as geraniums root well naturally. However, when the light levels and media temperatures are low, an application of rooting hormone can improve the uniformity and speed of rooting. Rooting hormone can be applied as a dip (1000 ppm IBA)
    or foliar spray (100 ppm IBA) until the foliage is completely wet. Conduct in-house concentration trials to find the optimal concentrations for specific cultivars
  • For the first 48 hours, mist the cuttings through the night on a regular basis. Thereafter, mist between 6:00 a.m. and 8:00 p.m. as required, to keep cuttings turgid
  • Do not let the cuttings wilt during the course of propagation. Alternatively, do not over-mist or over-water, as it results in leaching nutrients from the media
  • Maintain the daytime air temperature between 65° F (18° C) and 75° F (24° C) and the nighttime air temperature between 65° F (18° C) and 72° F (22° C)
  • Provide bottom heating between 72° F (22° C) and 76° F (24° C)
  • For geraniums, the pH should be between 5.8 and 6.2 and should provide an EC between0.75 and 1 mS/cm
  • Two weeks after insertion, water with complete a nutrient solution of 125 ppm N
  • Propagate cuttings under diffused light with light levels between 200 and 250 μmoles. m-2. sec-1 during the first week. After the second week, the light levels can be increased to 300 μmoles. m-2. sec-1. Cover the propagation area with shade curtains when the light levels go beyond
    350 μmoles. m-2. sec-1
  • Preventive sprays within 24 hours after insertion combined with proper venting and water management can help control Botrytis
  • Apply PGRs as required to keep cuttings compact. Pinching is not required during propagation
  • Generally, cuttings will be fully rooted and ready for transplant in 20 to 24 days after sticking
  • Do not let the Terra Plugs completely dry out during the course of propagation
  • Follow general transplant procedures

Research Conclusions:

Research trials demonstrated no significant differences in rooting response between Standard and Dry Terra Plug Mixes in the case of geraniums. Therefore, the Standard and Dry Terra Plug Mixes can be used interchangeably, depending upon the location, season, and greenhouse conditions.

The following are examples with Geranium ‘Fantasia Dark Red’

screen-shot-2016-09-21-at-11-00-29-am

Photos: Geraniums ‘Fantasia Dark Red’ 21 days after inserting into 72-count Terra Plug Standard Mix and Terra Plug Dry Mix (from left to right) – photos showing shoot growth (top) and rooting response (bottom)

 

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