Hydroponic Lighting Requirements – Complete Buyers Guide

The evolution in indoor grow lights has given hydroponic fruit and vegetable cultivation exponential growth. Hobbyists and commercial growers alike are choosing indoor growing as the go to option for farming and self sufficiency over traditional outdoor plots. With the right knowledge and know how, anyone can use the advantages that LED and full spectrum lighting has brought to the agricultural industry.

The most common lighting systems are LED, fluorescent, metal halide and high pressure sodium. Before purchasing a hydroponic lighting system, consider the following:

  • Flowering plants require a higher amount of light energy than leafy greens and herbs.
  • The dimensions and height of your grow space will dictate the amount of coverage you will need.
  • LED grow lights have become the go to option for hydroponic gardening. For most applications LED’s are the best choice.
  • Higher powered lights will consume more energy and cost more to operate. High efficient lights will pay for themselves in the long run.
  • The price of a lighting system will be determined by the overall quality, size and technology of the fixtures and lights.

So, if you’re enhancing or building an indoor garden, you need to set yourself up with the perfect hydroponic lighting system. Let’s dig into all the details needed to choose the best lighting system for your grow space.

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Best For Tall Flowering Plants


Different Types of Grow Lights

There are a number of different grow lights available on the market and each has a different characteristics that influence plant growth and flowering.

LED Lighting 

This is one of the newest forms of hydroponic lighting, and continued advancements in technology have made them better and cheaper than ever before. They have become one of the most cost-efficient and energy efficient methods of growing your plants. 

There are a lot of options in LED light systems. Some fixtures use a mix of blue and red lights while others use pink or white. This coloring is due to the light spectrum provided in the light. Plants use different light spectrums through their life cycle. Read more details on the spectrum below. LED Grow lights are usually either square panels or tubes similar to fluorescents.

Although LED lights are more expensive than the other bulbs on this list, they are also much more efficient and last longer. This will pay you back on your reduced energy and maintenance bills. Many LED Fixtures are rated for 50,000 hrs of run time. 

LED Light Application

LED lighting comes in a range of shapes and wattage making them suitable for nearly any indoor growing application. Low power tube style lights are great for seedlings and leafy greens above a horizontal grow area. They can also be mounted vertically to surround a vertical garden.

Higher wattage LED panels are great for taller plants that grow out of pots. The high power of the light can penetrate further past the top layer of leaves to reach the lower areas of the plants.

Fluorescent Lighting 

Fluorescent Grow Lights give off a blue hue and are ideal for the beginning stages of the growth cycle when seedlings are planted. The low heat of the lights will allow your seeds to grow without getting burned or dried out, they also work well for growing salad greens and flowers. 

Its wide light range will distribute light evenly to all of your seedlings, resulting in a smooth growth process. This type of grow light is usually found in 12”, 24” and 48” lengths with multiple tubes to a fixture. The most common types are T5 HO (High Output) grow lights, each bulb is rated for 20-60 Watts. 

Fluorescent Light Application

Fluorescent lights are great for tabletop growing of leafy greens and microgreens. The long lengths and low heat allow them to hang close to the plants without burning the tops. 

Metal Halide Bulbs (MH) 

The MH bulbs emulate the blue/white light spectrum and are made to mimic the sun’s light during the summer months. These are useful for long-day plants that require more light. MH bulbs help plants that have just finished sprouting and are now entering the growing or vegging stage. 

High-Pressure Sodium Bulbs (HPS) 

HPS bulbs have a more orangey-red hue to them. These lights are perfect for when your plants or fruits begin to flower. Both the MH and HPS bulbs are inexpensive to buy. However, they are known to generate a lot of heat, and they are incredibly bright, which means the cost of your electric bill will be much higher when these bulbs are being used.

Grow Light Spectrum
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Grow Light Spectrum

One of the most important metrics to pay attention to when choosing grow lights is the spectrum. Measured in nanometers (nm), the spectrum is the colour components of light. Plants use the different spectrums between 200 and 1300 nm for different purposes.

Selecting properly tuned full spectrum lights will allow up to 95% of the light energy to be consumed by the plants rather than producing unnecessary wavelengths that are reflected or wasted.

The PAR Values of Grow Lights

Photosynthetically Active Radiation represents the wavelengths in the visible spectrum of grow lights (400-700nm), they are measured using a PAR meter. 

The minimum PAR value to provide your plants is 250 umol/m2/s. A range of 500 – 600 umol/m2/s is the range you should target for healthy plant growth and development. 

Photosynthetic Photon Flux (PPF)

The amount of photons or light particles that are emitted by a fixture per second and is measured in micromoles per second (umol/s). The PPF of a fixture remains mostly constant but can diminish over time as the light gets older.

Photosynthetic Photon Flux Density (PPFD) 

A measurement of the number of photons that land in a square meter per second (umol/m2/s). The density will decrease as the light moves further from the plants, this is because the light spreads over a larger distance. 

It’s important to know a grow light’s PPFD rating for the distance you plan to mount it above your plants. This information is commonly found in a PAR Chart which illustrates the PPFD at different mounting heights.

How Different Spectrums Are Used By Plants

Blue spectrum

Blue is the 400 – 450nm wavelength, the low end of the visible light spectrum. It’s used in the vegetation and growth phase of younger plants and seedlings. This is the main spectrum found in fluorescents and Metal Halide bulbs and the reason they’re used early in the growth phase of plants.

The blue spectrum helps to reduce stretching of younger plants leading to a thicker and stronger stalk. This is important to supply the water and nutrients to the canopy and support the weight of the fruit and foliage.

Green Spectrum

The 500 – 550nm wavelength is closer to the center to the visual spectrum and is mostly reflected by the plant rather than consumed, that’s why plants appear green in color. Though the effect of the green spectrum on plants isn’t totally understood, a main characteristic is the vibrant look of the leaves and foliage under the light. 

Red Spectrum

At the other end of the visible spectrum is the red wavelength. 650 – 700nm is the wavelength that most influences the flowering. The red spectrum is often used to finish off the fruiting or flowering of plants but also has benefits to the growth phase as well. 

Red is the dominant spectrum associated with HPS lighting which is commonly used later in a plant’s life cycle. It mimics the sunlight found later in the growing season when many plants focus energy on flowering to seed the next year’s crop.

LED grow lighting is designed to incorporate all of the most beneficial wavelengths for the growth and flowering phases of a plant’s life cycle. Because a variety of colors can be used in a single fixture, full spectrum grow lights have a big advantage over traditional bulbs.

Grow Light Panel
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Grow Light Wattage

The lights, whether traditional bulb or light emitting diode (LED), are rated in watts. This is a measure of power consumption and energy for the plants. A higher wattage light will be able to penetrate further into a plant’s canopy hitting lower down leaves.

The watts are mainly consumed by the creation of light and heat, a light that produces less heat is generally more efficient and will deliver more light energy per watt to your plants. Individual LED chips come in 1,3,5, and 10 watt sizes, higher wattage chips need to be spaced apart for cooling which can lower the overall density of the light.  

How Many Watts For Your Garden Space?

The wattage is directly related to the intensity of your light. If you have a higher wattage fixture, you can put the light further away from your plant. The light will then cover a larger area. 

A good rule of thumb is to have 25-50 watts per square foot of grow space. This means a 500 watt LED grow light can cover 10-20 square feet. 

The caveat to increasing the wattage is the efficiency of your lighting system. Traditional bulbs are very inefficient compared to LED’s, this causes a lot of the wattage to be lost through heat rather than becoming light for the plant. A 500 watt LED light can provide equivalent ratings to a 1000 watt HPS or MH light. 

Providing the correct intensity, spectrum and cycle interval of lighting to your plants will ensure you get the maximum growth and harvests possible. 

Components of a Grow Light System

There are a few components of an indoor grow lights system you should be aware of when shopping around and researching the options. Some are directly related to the lights while others are used for control and environmental purposes. 

Light Fixtures and Ballast

The fixture is the main structure of the lights. It holds the bulbs, sockets, electrical wire and other components. Fluorescent ballasts are small devices housed in the top of the fixture and regulate the current and voltage for the bulbs.

The ballast for HPS and MH bulbs are the biggest and heaviest of the options. They are often located remotely to the fixtures with a long cord connecting them. Digital ballasts are dimmable and provide a soft start feature to protect the bulbs and help extend their lifespan.

Reflectors and Hoods

This is another critical piece of the hydroponic light system. Reflectors and hoods are used to direct the light that would otherwise be lost in a room toward the plants. They create a more efficient use of the light and distribute it more evenly. 

Reflectors and hoods connect to the light fixture and wrap around the back and sides of the bulbs. Reflectors can either be fixed or adjustable allowing you to better focus the light coverage on your growing area.

Using reflectors can increase the efficiency of your lighting system by 15% – 20%

Indoor Grow Tents

If you’re not in a greenhouse then you may be considering a grow tent to reflect the lighting back on your plants and contain your setup. 

Creating a barrier between your plants and the rest of your home will reduce odor and moisture problems and protect from contamination and pests. They come in closet sizes like 24” x 24” as well as room sized tents at 10’ x 10’ and larger. 

Most tents will have ventilation ports or piping to draw fresh air into the tent and also control the exhausted air. Ducting gives the ability to pipe the air directly out of a window or vent to the exterior of a building. 

Using a carbon filter connected to an inline fan is popular for scrubbing the air for moisture and odors. Common sizes of exhaust ducting is 4” or 6” flexible aluminum or foil pipe similar to a dryer vent.

Metal framed tents have overhead locations to hang your lights, fans, ducting and your carbon filter. The frame works well to control wire routing to lights and pumps as well as storage for smaller tools.

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Automatic Timers For Grow Lights 

Timers are inexpensive and do a great job at automating the light ON/OFF cycles. They come in both electric or mechanical options and are easy to set up and operate. Lights are operated on 24 hour cycle timers using 12-12 to 16-8 for a typical ON/OFF cycle. 

Choose a timer that can handle the power and current ratings of your lighting system, multiple timers may be necessary for large systems. A 15 Amp rated timer can handle up to 1500 watts comfortably, make sure you don’t overload the circuit or you could risk going dark or starting a fire.

Cost of Using Grow Lights

Lights are rated in Watts as mentioned earlier. Most electric utility companies charge for power usage in Kilowatt hours, which is 1000 watts per hour (1KWhr). If you have a 1000W light and you’re charged $0.10/KWh by your utility company, running on a 12-12 cycle would cost $1.20 per day or $36 per month. 

Efficiency plays a big part in grow lights because the power consumed is transferred into light and heat energy. Too much heat can burn or dry out the plants, it is also a waste of power in comparison to cooler running lights like fluorescents and LED’s.

Any light fixtures using traditional bulbs, fluorescent, MH, HPS, etc will need more maintenance than LED fixtures. LED lights produce less heat and last 50,000hrs or more. Bulbs need to be replaced more often translating to a higher cost over time.

Best Grow Light For Microgreens and Salad Greens

Low profile plants like microgreens and salad greens don’t require high powered lights because they don’t grow tall. I use Barina Full Spectrum LED Strip Lights because they cover a lot of surface area and are very energy efficient. 

Each 42 Watt T8 fixture provides the equivalent of 230 Watts of lighting for the plants with very little heat and a lifespan of 50,000 hours. The lights are very bright but don’t bother my eyes like many of the colored light fixtures do.

The all aluminum body keeps the lights from getting too hot and causing damage, it also has integrated reflectors to concentrate the light on the plants making it more efficient. 

I love how the fixtures are plug and play. By connecting all 6 of my lights together, I only need 1 timer to run the whole setup. You’ll find all the cords, switches and mounting hardware in the box. Just open it up and plug it in!

Barrina Plant Grow Light, 252W(6 x 42W, 1400W Equivalent), Full Spectrum,...
  • Full Spectrum - Barrina 4ft LED grow lights provide indoor plants with full-spectrum sunlight...
  • Super Bright and High PPFD - Consuming only 252W with 1152 LEDs totally, replace 1400w general...
  • Easy Installation - With included tape, clips and cable ties, you could install the lights by...

Best Grow Lights For Tall and Flowering Plants

When growing taller flowering plants like tomatoes I use a higher wattage light to penetrate below the canopy. The high performance PB series from Maxsisun does exactly that for my setup. 

Available in 1000, 1500, 2000 and 4000 Watts, These full spectrum LED grow light panels cover a large grow space or tent at a height of 12 to 24” above my plants. 

The commercial grade panels are cooled through the aluminum back plate which eliminates the wasted energy and noise of a fan. Both the panels and ballast are fully waterproof and the included mounting hardware allows me to adjust the fixture height throughout the growth cycle. 

At double the efficiency of my old HID lights, I get a lot more grow with a lower energy bill. 

In Closing

Buying a lighting system should not be stressful, and with the guidance provided in this article, you’ll be able to purchase a light system that suits your grow space.

Beau McManus

I love to grow great food and eat great food. Controlling the quality and supply of my food has always been a passion.

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