With all the choices in grow lights that exist, choosing one may seem difficult, especially for those not accustomed to indoor gardening. Different lighting products offer different advantages, such as promoting full growth or promoting better blooming. This is especially true with fluorescent and high pressure sodium (HPS) lights. Some may even use both of these lighting products together to get the best results.
Most plants need light so that they can generate the energy they need through photosynthesis. Plants use chlorophyll, a chemical that gives plants their green color, to change light into sugars, which are then used for growth and reproduction. Without adequate light, plants will not reach their maximum potential and may even die. Both fluorescent and HPS lights provide the basic lighting plants need but also do some things that may make one preferred over the other, depending on your situation.
The main advantage of HPS is that these lights provide more light at the red end of the spectrum. The red end of the light spectrum is more useful for plants that are blooming, or that you want to bloom. Therefore, if you have flowering plants that have achieved full growth but are not blooming as you may expect, HPS lights are a good choice. HPS lights also produce approximately 140 lumens per watt, making them a strong light source for plants.
Though you may be tempted to use HPS lights full time, especially if you are growing flowers, this may be a bad strategy. Red light also promotes vertical growth, at the expense of full vegetative growth, which can make plants look thin and sickly. Therefore, the best option is to only use HPS lights with a full spectrum light source, such as natural light or even fluorescents.
The full spectrum lighting that fluorescents offer is a major advantage, but not the only one. Fluorescent lights also provide the opportunity to keep the light close to the plant, because they give off very little heat. In addition, fluorescent bulbs last a long period of time and use very little energy, making them one of the most economical lighting options for indoor gardens and greenhouses.
One of the major disadvantages to some fluorescent lighting products is the lumens they produce. Many do not produce enough light to be much of a benefit to plants. You need to find bulbs that produce at least 75 to 90 lumens per watt. Also, remember that fluorescent bulbs cannot be used as a supplemental heat source.