Depending on the geographic location and the plants you choose to grow, it is possible that your greenhouse will require, during at least part of the year, a supplementary source of light, both for plant growth and for general operation. Grow lighting can be used in the winter, or even on cloudy summer days to simulate the sun and light that plants need to develop. Such light is particularly important if your crop production schedule is tight, or if you have a short growing season. The development of photoperiodic lighting, which artificially simulates long days, can benefit different varieties of plants and accelerate flowering.
Supplemental greenhouse lighting can be controlled by a manual on/off switch, with a timer, or by sensors that automatically detect low-light levels and have the ability to activate grow lights for the plants. In addition, every greenhouse will require general illumination and specific task lighting. Site security lighting may also be important. Greenhouse lighting needs should be considered as part of the overall electrical plan and service. It is deemed wise to provide for system redundancy and/or a backup generator in case of severe storms or prolonged power outages. Spending money to prevent system failures is a wise investment, compared to the cost of losing a crop and the potential loss of revenue and customers. Even a greenhouse for residential use would benefit from some sort of alarm system to alert owners of potential problems or imminent danger. With today's wireless technology, it can be relatively easy to install such systems, and they offer 24-7 monitoring capability.
