Explanation of Greenhouse Lighting and Explanation of Photosynthesis Process

Greenhouse Lighting


Plants use light to create chemical energy to fuel the organism’s activities. The process is called photosynthesis. Most species of plants require the same amount of sunlight, but this can vary upon the species. Most cuttings require 8-12 mol/m2 /day, bedding plants require 10-12 mol/m2 /day or greater and vegetables can vary. Plant growth is categorized by two types.  These two categories are plants that will not grow more than 15”, and plants will grow over 15”.  The creation of light can occur in three different ways and are measured by different light qualities.


Fluorescent Lighting

Best for low growing plants

Bulbs can be operated 12-16 hours daily

Close to 4”-6” of the plants

Wide or full spectrum bulbs

Put off very little heat

Can mimic real daylight

Can hang from the roof rafters, freestanding structure

Used for germination


High Intensity Lighting

Used for plants over 15” tall

Energy is effective much farther away

2 different types- Metal Halide and High Pressure Sodium

MH provides full light spectrum

MH is most effective for indoor use with

HPS has extra red, yellow, orange spectrum

HPS used for supplementing real light