Light is essential for plant growth. Light makes it possible for plants to carry out photosynthesis which provides energy for plants to grow. Plant lighting - sometimes called grow lighting - is an artificial light source, normally electric, that enables you to ensure your plants get sufficient light for healthy growth. You can divide plant growth into two key periods - vegetative and flowering. For healthy vegetative growth plants need to be exposed to blue spectrum light. For successful flowering plants need red/orange spectrum light. You can therefore select your lighting system based on what you want to grow.
Metal Halide Bulbs(also known as MH lights) provide a blue light that promotes green growth, shortening internode spacing and preventing 'leggy' plants.
High Pressure Sodium Bulbs (also known as HPS lights) provide a red light to promote flowering growth in the later stages of plant growth.
Although you can choose to use one type of light throughout the whole period of plant growth, for the best results we recommend the use of MH lights at the beginning of plant growth and swop to HPS lights as the plants mature to encourage lots of flowers.
The other option is to choose a plant lighting that provides full spectrum light, like the Mercury Lighting System.