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Choosing the best grow light for a beginner grower can be a daunting task. A simple Amazon search for “grow lights” will yield hundreds of different grow lights for all types of cultivators. Everything from $5 incandescent lamps to expensive high-tech commercial LED or HID lamps can be found. But which light will best fit your setup?
Below is an explanation on how different plant types react to different grow lights as well as a list of some different types of grow lights, their pros and cons, and how you can use them for your indoor growing.
LED Grow Light growing a Bird of Paradise. Photo credit to @carmeon.hamilton
Which growlight light is best for my indoor garden?
When searching for the proper lighting for your indoor garden, a common question that may come up is “Which light is best for my plants?” This question has many different factors to consider before a concrete decision can be made. Firstly, which type of plants do you have in your garden? If you have plants that are leafy greens, seedlings or have lots of foliage, it would be best to have lights with cooler spectrum bulbs (6,500 K). If you have flowering or fruiting plants such as citrus, warmer spectrum bulbs (2,500 K) will be best suited. The next question that you may find yourself asking is “What does K stand for?” K is short for Kelvin, a scale of temperature measurement.
Similar to Fahrenheit and Celsius, the lower the number, the cooler the temperature. However, the light spectrum acts in the opposite manner; (the lower the number the warmer the light). The last piece of information that can be useful to know is what color corresponds to what side of the light spectrum? Warmer light tends to be yellows or reds while colder lights tend to be blues and whites.
What is the light spectrum and how does it relate to my garden?
The electromagnetic spectrum is a wide range of frequencies of electromagnetic radiation. In Layman’s terms, there are invisible waves all around us with different sizes and speeds. These waves are so small that they are measured in nanometers (nm). A nanometer is one billionth the size of a meter. Some more well-known parts of this spectrum include X-rays, microwaves and radio waves. One part of the spectrum that you may not realize is part of it is the visible light spectrum.
This portion of the electromagnetic spectrum is the only part visible to the unaided human eye. These waves range from about 400 nm to 700 nm. The classic acronym “ROYGBIV” that was used to remember the colors of the rainbow can also be used to remember the order of the visible light spectrum. Red is at the upper end of the spectrum (700 nm), violet is at the lower end of the spectrum (400 nm) with yellow/green light in the middle (~550nm).
You can use this information to better understand which light produces these wave frequencies in order to provide the correct color of light to your plant. There are 3 main types of grow lights, compact fluorescent (CFL), high intensity discharge (HID), and light emitting diodes (LED).
Compact Fluorescent Lights (CFL)
Fluorescent lights (CFL) typically come in long, tube like bulbs in a range of sizes including T5, T8, and T12. They are ideal for plants that require low to medium light, such as African Violets. When growing most houseplants, use light bulbs between 4000 and 6000 Kelvin, as the bulb’s color temperature will borrow from a full spectrum of colors—cools and warms.
Culinary herbs, greens and starter plants can be grown year-round with them. Houseplants that need lots of light, like cattleya orchids, succulents and carnivorous plants, also perform much better under these full-spectrum lights.
CFL over seedlings sourced via Aaron von Frank of growjourney.com
These can be found in many stores including home improvement & grocery stores. Many first-time growers start with these types of lights. You can purchase the two lamp “shop light” variety for under $40 at your local hardware or garden supply store.
Pros of CFL Lights:
- Inexpensive
- Good for small grows
- Available in many stores
- Works in any standard light fixture
- Available in various color temperatures
- Good for beginner growers
Cons of CFL Lights:
- Low light output compared to other types of bulbs
- Need to be close to plants
- Need to use several
- Not meant for bigger grows
- Inefficient
- Not for intermediate/experienced growers
High Intensity Discharge (HID) Grow Lights
High Intensity Discharge lights is a family of lights that produces light through an electric arc. This arc is formed when electricity is put into the bulb and it connect to both electrodes. This is different from incandescent bulbs as they do not require a filament to heat up to produce light.
HPS light over plants sourced via zenhydro.com
The HID family can be broken down into two different types; High Pressure Sodium (HPS) and Metal Halide (MH) lights. These lights both use the same principle, running electricity through an arc to produce light, however they use a different substance in the arc to produce light. As the name may suggest, HPS lights use highly pressured sodium which reacts with the electricity to produce a red and orange color. MH lights uses halides (such as Bromine or Iodine) and metals (such as Mercury) to produce a similar reaction, except this reaction produces blue and white light.
Both of these lights can be expensive to purchase and operate, however, they are very efficient. HID lights produce lots of light and the blue light of MH lights will promote vegetative growth, however it also results in less flowering. The red to orange hue of HPS lights are powerhouses when it comes to producing buds and flowers, but plants will be less sturdy.
Used in tandem, MH lights are often used to promote leafy growth before swapping in HPS lights to encourage plants to flower. It is also noteworthy that these lights need a significant warm up time and it is not ideal to turn one on before letting the metal chamber fully cool down. These lights are used by experienced growers, as many of them consider HIDs to be the best for growing and obtaining the highest yield.
Pros of HID Lights:
- Costs less than other high-quality lights
- Produces great results
- Easy to setup and operate
- Higher quality than normal incandescent lights
Cons of HID Lights:
- Produces a lot of heat, requiring ventilation and exhausts.
- Limited lifetime
- Does not plug into a normal socket
- Requires special hood & ballast
- Needs significant warm up time
- Can significantly increase electric bill
Light Emitting Diode (LED) Grow Lights
LEDs are the new technology when it comes to grow lights. As technology advances these lights become more and more efficient for your plants. The lights emit virtually no heat and require a fraction of the power to operate compared to other lights. LEDs can be programmed to fully optimize the light spectrum needed for each of your plants, however this can be very expensive to do. It is also important to know the difference between LED grow lights and regular LED lights.
Regular LED lights are the kind you can find college kids using to make their room or car look cooler. LED grow lights will need a certain wattage (measurement of power) to produce certain brightness. The good thing about current day LEDs is that the manufacturers often list the wattage in comparison to other types of lights, which can help a consumer make a better judgment on which specific bulb they should get so they do not make their electric bill skyrocket.
Aspect™ LED Growlight over kumquat by @goldalamode
LEDs are able to produce enough light intensity for the most demanding grows, and the right LEDs can compete with or beat other types of grow lights. These lights can be both red/violet or white in color. Please be wary of cheap knockoffs that can be found all over the internet. Just remember you get what you pay for, so do your research and find the perfect one for you!
Pros of LED Grow Lights:
- The most energy efficient grow light
- Barely produces heat
- Plugs into standard outlet
- Long lifetime
Cons of LED Grow Lights:
- High initial costs
- Can be confused with regular LEDs leading to misinformed purchases
