Growing Cannabis? Here is what you need to know about the Daily Light Integral (DLI) for Johannesburg

  • Posted by j4m3s_n1md
  • On 2020-01-27
  • cannabis lighting, lighting for cannabis

When growing cannabis, supplemental lighting is essential if you are growing in a greenhouse which significantly cuts down the amount of light that actually reaches the plant. To increase the quantity and quality of your cannabis harvest it is recommended that you add supplemental lighting.  Whilst the lights may only be on for a few hours in the summer months to reach the optimal DLI, this will need to increase during the winter months as illustrated in the graph below.

  • Apart from increasing yield and potency, supplemental lighting allows for more harvests per annum.
  • Good quality LED grolights can deliver DLI of 3.0-3.5 per hour.

However, excess light can damage your cannabis plants as much as too little light. Talk to us about your lighting requirements.

Source: Green Power, 2020-1

LED v HPS Lighting technology

LED Impact:

  • Higher capex
  • Increased revenue from higher yield & potency
  • Reduced load on cooling equipment
  • Avoids HPS re-lamping issues
  • Payback can be as little as 2-3 years

Source: Economic Impact of Light Intensity on Yield and Secondary Metabolites, A. Justice & J. Gerovac, Photox Summit, San Diego, 2017

Investment in lighting

  • Investment in supplemental lighting is considerable –
    • Capex of R3-6k per m2 of green house (depending on veg or flower) and the fitting actually selected.
    • Opex of 600-800kWh p.a. per m2 of green house (depending luminaire & veg or flower)
  • Infrastructure requirement – power to site (work with Eskom during planning phase to minimise grow-time losses)
  • Must sweat assets – more harvests with higher yield and potency
  • Clone plants to shorten time to harvest and improve crop consistency
  • Off-take agreement must cater for quick monetarising of crop

For more information contact:

T: +27 (0)11 312-5430


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