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News and Best Practices

Managing Plant Health for Optimal Quality and Yield: Notes from CannaGrow

May 16, 2016

Long-time grower, Cannabis Cup winner, and cultivation consultant Jennifer Martin, shared her tips for managing plant health at the CannaGrow conference May 8th and 9th in San Diego. Following are the highlights from her presentation.

Presenter: Jennifer Martin, Cultivation Sector. A leading cultivation consultant
Contact information: http://www.cultivationsector.com/cannabis-cultivation-consulting.html

The five items you need to balance to maximize quality and yield:

  • Light—intensity and type
  • Air—temperature, humidity, freshness and circulation
    • Temperature should be varied by plant stage, and location (air vs root zone temperature)
    • Freshness encompasses open vs closed systems
  • Water—Quality and quantity
  • Food—pH, quantity, ratios and availability
    • pH is the number one problem in commercial grows
  • Combination issues—various items above in combination with one another

Limitations professional cultivation operations face relative to testing:

  • Meters—light and air
  • Water analysis—site and lab
  • Soil/reservoir analysis
  • Tissue analysis—leaf, stalk, flower and sap
  • Where to send samples for testing, and what can and can’t be sent

Testing recommendation for professional grows: conduct rootzone combined with plant sap on all 13 elements once a week.

Complications facing professional growers:

  • Compounds are not a 50/50 mix (for example, N2SiO3, MgSO4)
  • Soils are negatively charged, including Coco
  • Synthetic fertilizers have high sulfur and chloride by necessity of design
  • Most organic fertilizers have high sodium and/or chloride
  • High nitrogen and phosphorus are also common
  • Plants have various tolerance windows for each mineral (such as Ca and B)
  • Implications for growers—run-off and testing are essential

Other factors that have to be balanced:

  • Bio-stimulants
  • Flushing/leaching
  • Worker proactivity
  • Foliar sprays
  • Pruning
  • Air movement

Parting thoughts:

  • Measure and test every possible metric frequently, but don’t stop using your senses
  • pH out of range is the first thing to check when there is a problem Food excess/imbalance is next
  • Sick plants always do better with less light and water until they heal
  • Avoid excess variables and over-complication
By Tom Brooksher, Executive Editor

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