Choosing the Right Grow Light

Hydroponic gardens usually don’t rely solely on natural lighting; some use a blend of natural and artificial light, and many are completely lit artificially.  Plants utilize different parts of the light spectrum at different stages of growth.  The lights used in hydroponics are called “grow light”, appropriately named because they are designed to emit light that make plants grow!  Because artificial lights can’t cover the full spectrum that natural sunlight can, it’s important to use the right kind of grow light for the kinds of plants you’re raising, and it’s important that the correct lighting be used at the right stage of growth.  Here’s a little bit of information to help you make those decisions.

For the early growth of plants, and/or for leafy types of plants, the blue-white side of the color spectrum is best.  Metal Halide (MH) bulbs are very good at providing this kind of light.  They are a High Intensity Discharge bulb (HID), meaning they burn hot but can provide the necessary lighting without being placed too close to the plants.  Plants grown exclusively under MH bulbs tend to be thick, leafy and compact.  MH bulbs are used as the primary lighting source in many gardens.

During the blooming stage, plants draw more from the orange-red side of the spectrum. High Pressure Sodium bulbs (HPS), another kind of HID grow light, are very good at this stage of plant growth.  Because of their limited spectrum, HPS bulbs are not a good choice as a primary source of light, but are best used as supplemental to other kinds of lights (like MH), or to supplement natural sunlight.  Otherwise, your plants will grow abnormally tall and thin.

If you are primarily growing seedlings (or if you have a separate area for the seedling stage of plants), a great choice for your grow light is standard fluorescent lighting, placed close to the seedlings.  Standard fluorescents cover a good part of the light spectrum while emitting a low intensity—a near perfect condition for seedlings.  They also emit low heat, so they can be placed close to the young plants without burning them.  In other applications, the low intensity of standard fluorescent bulbs isn’t very conducive to growth.

Many hydroponic gardens use a combination of different grow lights, but if you are limited in your budget and/or prefer to keep things simple, high-output fluorescents are a great choice.  Unlike standard fluorescent grow lights, the high-output bulbs offer a more intense light with low heat, and can be arrayed to cover almost the entire spectrum of natural light.  Although less intense than HID bulbs, they are also less expensive; and because they are cooler, they can be placed much closer to the plants to compensate for the low intensity, with excellent results.

Choosing the right type of grow light for your hydroponic garden can be intimidating, but knowing how different types of light help your plants grow will help you pick the right grow lights for your garden.