Grow lights are possibly the most important part of a successful indoor garden. In this article we will help you understand the fundamentals of how light works and discuss the different types of grow lights. This will hopefully help you make an informed buying decision and have a deeper knowledge of how grow lights work.
There are many types of grow lights, each one has its pros and cons along with different uses. Let’s first discuss some basics of how light works and what kind of light plants need.
Light spectrums are measured by their electromagnetic frequencies in nanometers (one billionth of a meter). Sunlight, which plants turn into energy for growth, is in the visible spectrum of light. Humans see this as green, yellow, and orange. Plants also use this light, but also use more of the red and blue frequencies. The blue and red frequencies range from around 400nm to 700nm.
Grow lights output different frequencies of the light spectrum. This is important to understand because during the vegetative phase of growth the plant will need more of the blue spectrum. The blue spectrum is the type of sunlight we see in the spring time. During the fall, the sun outputs more of the red spectrum. So, when your plants are in the flowering or fruiting stage of growth they will need a light bulb that produces light in the red spectrum to simulate the autumn sunlight.
Light output is normally measured by lumens or PAR. This can get a bit complicated and we will cover this in another article.
Types of Grow Lights
High Intensity Discharge(HID)
High intensity discharge lights are a very popular grow light. These lights are much more efficient than fluorescent CFL bulbs. These lights are also used in industrial or commercial situations like a car parking lot or inside a large factory. HID grow lights normally need adequate ventilation because they can get very hot. This heat must be considered when building your grow room or using a grow tent indoors.
HID grow lights can use two different types of light bulbs called High Pressure Sodium (HPS) or Metal Halide (MH). Normally, HID grow lights have an external ballast to power them. The ballast powers the bulb and regulates voltage. Electronic ballasts are preferred over mechanical ballasts because they are quieter, more efficient, and can use HPS or MH bulbs. Some grow lights have the ballast build into the lamp. These are lower powered grow lights and do not get as hot as some of the higher powered models.
High pressure sodium bulbs produce light on more of the yellow and red spectrum. This is idea for flowering or fruiting because it simulates the fall season.
Metal Halide is normally used for the vegetative stage of the plant because it produces the blue spectrum they need. Growers will start with a metal halide bulb then switch to an HPS bulb during the flower stage of the plants life cycle.
Fluorescent Grow Lights
Fluorescent indoor grow lights decent grow lights especially for young plants or small plants. They do not have the output or efficiency of HID grow lights, but can be a good option if you’re using high-output fluorescent bulbs. These also run much cooler than typical HID grow lights. Fluorescent lamps have bulbs available throughout the light spectrum and can be used for vegetative and flowering stages.
CFL Grow Lights
Compact fluorescent grow lights are commonly used in households. These use much less power than typical incandescent blubs. CFLs are perfect for small budget indoor gardens.
T5 Grow Lights
T5 grow lights are very popular grow lighting and are much larger than CFL bulbs. T5 lights are usually long shaped and come in multi-bulb lamps. These lights do not get very hot and can be used in smaller spaces close to the plants.
LED Grow Lights
LED grow lights are a newer type of grow lighting. LEDs are super efficient bulbs and can use around 60% less power than high intensity discharge (HID) grow lights. LEDs typically run much cooler than HIDs, but still produce some heat and depending on your grow room configuration, you might need ventilation. LED grow lights come in full-spectrum and can be used for all stages of plant growth. LEDs can be a bit more expensive upfront, but use a lot less electricity compared to HID grow lights.