Maximum Yield Cannabis Canada 2017 November/December | Page 50

light planning
TIPS
1. A TRUE
HORTICULTURAL
LIGHTING SUPPLIER WILL
ALWAYS SPECIFY LIGHT
LEVELS IN MOL/M 2 /S
(that is, PAR photons delivered per square metre
per second). This is a measure of the light that plants react to,
rather than lumens, lux, or footcandles, which are measurements
based on the wavelengths that the human eye can detect.
2. LIGHT UNIFORMITY (an indication of how uniformly/
evenly the light intensity is distributed across the surface of the
crop) is a key metric to consider in a light plan. Always look at
the min/max ratio on the light plan for a true indication of light
uniformity, rather than the min/average uniformity.
3. ALTHOUGH YOU SHOULD ALWAYS
CONSIDER THE CUMULATIVE OPTOMETRIC
PERFORMANCE OF THE LUMINAIRES in a given
application, the polar distribution curve of a luminaire can
provide a good initial indication of the type of distribution
expected from the luminaire. Look at the ratio of highest (A)
to lowest (B) illumination points on the curve. The closer the
ratio is to one, the more uniform the distribution. An added
advantage of lighting systems that deliver high-uniformities,
is that they enable wider row spacing, meaning you can
achieve the desired light levels with fewer light fixtures.
Optimal light distribution (top) vs. sub-optimal light
distribution (bottom).
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grow cycle