The types of light bulbs used to produce artificial light generate a lot of heat. If the bulbs are not cooled, they can end up burning, dehydrating, stunting, and feeding deadly funguses. There are many different types of grow lights on the market. The lighting system used for each grower will depend on the plants being grown and the scale of production. The types of available hydroponic bulbs are listed and described below.Types of Grow Bulbs

Metal Halide (MH):

Most popular among growers due to their excellent light wave spectrum distribution. They provide high quality mid-summer sun imitation light which allows photosynthesis to occur at an optimum rate. There are also specialized bulbs that range from “cool” to “warm”. The higher the number of Kelvin units it emits the “cooler” the spectrum rating is. Cool spectrum bulbs ranging from 6.4K-10K are used for vegetative growth. Bulbs with a range of 2700K-3000K are used for plants that are flowering or fruiting. Metal Halide bulbs also have a long life expectancy and high lumen maintenance. Lumen maintenance refers to the lumen output of a bulb over its life time. The best practice is to replace them once a year.

Recommended Brands:

Sunmaster Cool Deluxe, Hortilux Blue, Digillux MH, and Standard MH Bulbs

High Pressure Sodium (HPS):

These are the second most popular grow lights. They have good spectral distribution, but are very lacking in the blue light spectrum which stimulates chlorophyll production. They are high in the yellow and red spectrum of light waves. This light spectrum stimulates the release of hormones within the plant. This means they are good for initiating the budding, flowering, and fruiting stages of growth. If they are the only light source the plant will eventually become thin and leggy. For this reason, they are most commonly used in conjunction with metal halide bulbs. An advantage of high pressure sodium bulbs is that they have a two-year life span.

Recommended Brands:

Hortilux Super HPS, Sunmaster Super HPS, Agrosun Red, and Digilux HPS


LED or light emitting diodes are the newest form of hydroponic lighting. They are ecofriendly and cost effective. They produce very little heat and have four times the life span of fluorescent bulbs. These lights contain many red and blue colored diodes. The recommended ration of diodes to create a healthy light spectrum are 10 blue diodes for every 1 red diode. They must also be placed close to the plant at 3 to 12 inches from the leaves. Plants grown in optimum conditions are smaller, denser, and have tight inter-nodal growth. They grow, flower, and fruit at a slower rate, but tend to be very hearty. The fruit and flowers produced from led grown plants are more vibrant and colorful than ones grown with traditional lighting.

Recommended Brands:

California Light Works Solar Storm, Joy Hydro Grow Pro, Apollo Horticulture Full Spectrum, Lighthouse Hydro Black Star Flowering, and Miracle

Compact Fluorescents (CFL):

They are used primarily in small spaces containing a few plants. They do not generate a lot of heat and are energy efficient. They are especially favorable for seedlings, cuttings, and small young plants. Fruiting and flowering plants need a 2700K warm bulb. For the rest of the year a 6400K bulb will be adequate. These bulbs are the size of regular household lightbulbs and do not require the large bulky housing of traditional fluorescent tubes. This allows multiple bulbs with different light spectrums to create full spectrum lighting.

Recommended Brands:

Feliz, Pro-Start, and VitaLUME


Fluorescent tube lighting has progressively increased in quality. The original T12 bulbs are being phased out of the market entirely. They have been replaced with the better T8 and T5 bulbs. T5 bulbs are the best for hydroponic plant growth. They work very well for small seedlings and household plants up to 12 inches tall. These bulbs range in spectrums from 6400K to 2700K. A combination of these is recommended to create a full spectrum light source. The tubes are about a yard long and housed in a rectangular ballast that requires multiple bulbs.

Recommended Brands:

Agrosun, Feliz, G.E., Hortilux, Pro-Start, Spectralux, Sunleaves, and VitaLUME