Plants & lighting

Watts, Lumens, Photons and Lux

As the importance of artificial light in the plant growing industry has increased, lamp manufacturers have begun to rate lamps specifically for plant needs. This article discusses and compares the different measures of " light level" that are currently used for plant growth and hydroponic applications. Light level is one of the important variables for optimising plant growth, others being light quality, water, carbon dioxide, nutrients and environmental factors. The appendix describes a step-by-step approach to developing a simple lighting layout using the PAR watt ratings of light sources.

In recent years, it has become increasingly cost-effective to use artificial lights for assisting plant growth. Lighting costs and lamps have become less expensive, and very efficient light sources are now available in high wattages. These developments along with the ability to preserve and transport plants and produce as well as special new products in demand today have resulted in a lucrative market for hydroponic products, that is, products grown without soil.

Artificial light can be used for plant growth in three different ways:

  • To provide all the light a plant needs to grow

  • To supplement sunlight, especially in winter months when daylight hours are short

  • To increase the length of the "day" in order to trigger specific growth and flowering


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This is an image of Sunmaster Grow Lamps in a green house