Hydroponics is an agricultural method of growing plants in a water-based, nutrient-rich solution. It is drawing attention as one of the most exciting advancements in agriculture today. At Eden Green Technologies, we're at the forefront of AgTech. We use hydroponic lighting to grow sustainable produce in our vertical farms.

Instead of planting crops in the ground, hydroponic produce is grown with roots dangling in water. This water is recycled through the system constantly, and nutrients are added to it to ensure the health of the plants.

This agricultural technology allows growers to produce fresh, healthy hydroponic foods. They can grow crops indoors year-round, regardless of weather or climate, and with no soil needed. 

It's an excellent way to bring agriculture into densely populated urban areas. Doing so shortens food miles and offers fresher foods that will last longer in stores or at consumers' homes before spoiling. 

Of course, growing plants indoors and out of season presents some challenges. You'll want to include several types of hydroponic technologies to ensure the greatest possible yield. One of the most significant technologies to consider is hydroponic lighting.

Why is Hydroponic Lighting Important?

Traditional farms get all the light they need from the sun. But when you choose to grow crops indoors, you typically need to replace at least some of this natural light with artificial options. This is where hydroponic lights come into play.

Greenhouse operations can harness the sun’s light for much of their plants’ needs, but this may not be enough. When sunlight is less available, even glass greenhouses will need to supplement with artificial light.

Light Requirements for Hydroponic Plants 

Since most hydroponic systems are housed indoors, they need artificial light for plants to grow and thrive. But what exactly does a hydroponic light system involve? Growers must consider several factors when choosing hydroponic lights.

Photoperiod: Understanding Light Duration’s Effect 

The time period within any given 24 hours in which a plant or other organism receives light is called the photoperiod. The way a plant responds to the photoperiod is called photoperiodism. This can have drastic effects on the plant’s growth and health.

In general, plants determine the season by the length and quality of light they receive. In the summer months, days are longer and outdoor plants receive more light. In the winter, the opposite is true. For tropical regions, this seasonal shift is minimal, while cold climates see a dramatic change from season to season. 

When growing hydroponic plants indoors, you want to mimic the photoperiod of the months when your plants would naturally thrive outdoors. Consider not only the seasons when these plants thrive but also the regions in which they are typically grown. 

You’ll also want to adjust the photoperiod as the plant grows. If you’ve chosen a crop that is traditionally planted in the early spring, lengthen the photoperiod as the plant grows. For plants that are sown in late summer, you’ll want to shorten the photoperiod over time. 

Light Intensity and Its Effect on Plant Growth 

Beyond the amount of light a plant receives each day, the intensity of that light will significantly affect the plant’s growth and health. The AgriLife Extension at Texas A&M puts it this way:

“Light intensity influences the manufacture of plant food, stem length, leaf color, and flowering. Generally speaking, plants grown in low light tend to be spindly with light green leaves. A similar plant grown in very bright light tends to be shorter, have better branches, and have larger, dark green leaves.”

Much like photoperiods, you’ll want to tailor light intensity to the type of plants you’ve chosen. Low-light plants actually grow perfectly well with less brightness than high-light varieties. That said, it’s generally best to err on the side of too much brightness. 

Light Spectrum: Blue, Red, and Beyond 

The color of the light that plants receive is also important. Color is determined by the frequency of light waves, often measured in wavelengths or nanometers. The visible spectrum we can detect runs from 400 nm (violet) through 780 nm (red). Outside of this spectrum are wavelengths like UVA (315-400 nm), UVB (280-315 nm), and infrared (700-1,000 nm). But what does this mean for plants? 

Different lighting wavelengths will have different effects on plant growth. Aydinlatma Portali (translated The Lighting Portal) presents a helpful guide for how each color impacts our crops. The lowest wavelengths cause plants to flower, while the highest can increase yields. Because of these differences, most indoor growers use several lights in different colors. 

Hydroponic Light System Components 

When setting up your indoor lighting for hydroponic plants, there are several components you'll need. These include bulbs, a reflector hood, a remote ballast, and a timer to run the system.

Bulb Options for Hydroponic Lights

While you can grow plants with nearly any sort of bulb, some types of light will produce healthier plants than others. Below we'll detail a few of the most common bulb options for hydroponic grow lights: 

LEDs (light-emitting diodes) 

LEDs, or light-emitting diodes, are probably the most common type of bulb used in hydroponic lighting. They are easy to find, use less energy than most options, and produce very little heat. LEDs also offer plenty of light intensity and need no warm-up period to produce bright light. 

LED lights are sometimes more expensive up front, but they are known for their long lifespan and do not degrade with repeated switching on and off. Growers should be aware that many LEDs may lose intensity over time, so you may need to supplement older bulbs as they degrade. 

LEDs are available in various colors, and many growers choose to combine several individual colors to create a broad spectrum. You can also buy programmable LEDs that can change colors based on your needs.

Fluorescent bulbs 

Fluorescent bulbs are another favored option for hydroponic light systems. They’re fairly cheap and come in both cool and warm color variations. They initially cost less than LEDs, but typically LEDs are cheaper in the long run because they will last longer and use far less energy.

Fluorescent bulbs work by running electricity through low-pressure mercury vapor. This excites the mercury gas and produces ultraviolet light. The UV light then reacts with the phosphor coating inside the bulb to produce fluorescent light. 

One significant downside to fluorescent bulbs is that they are classified as hazardous waste because they contain mercury. Growers using these lights are responsible for safely disposing of them or recycling them. 

Metal halide (MH) bulbs 

Metal halide bulbs are used because their spectrum contains a relatively high percentage of blue light. They’re best employed during the early stages of growth.

Much like fluorescent bulbs, metal halide bulbs contain mercury. This means you will need to properly dispose of the bulbs once they’ve stopped working. MH bulbs also have a tendency to lose intensity throughout their lifespan. Growers should carefully track light output and supplement or replace these bulbs as they lose brightness.

High-pressure sodium (HPS) bulbs 

These bulbs tend to offer a red or yellow light color spectrum. They are most frequently found in traffic lights but are also preferred by indoor growers during the late stages of plant growth.

HPS lamps tend to be very energy efficient, meaning they are less expensive to run than many options. One problem to watch for is cycling as they reach the end of their life. If you’ve ever noticed a street lamp flickering on and off, you’ve seen this type of cycling in action. The bulb will turn itself on and off repeatedly until it simply can’t turn on again. When this happens, the bulb needs to be replaced.

Reflector hood 

Once you’ve chosen the bulbs for your hydroponic lighting, you’ll need a reflector hood. These devices sit behind the bulbs and reflect the light back toward your plants. A good reflector hood can offer an enormous lighting efficiency boost by redirecting light toward your plants. 

Remote ballast 

Plants need a steady light source to grow well, and ballasts are one way to achieve this. They work as power transformers and ensure that your lighting receives a regulated flow of electricity. While on-fixture ballasts are an option, they may put out too much heat for your plants to thrive. Instead, most growers prefer a remote ballast option. This keeps excess heat away from delicate plants and makes temperature regulation easier. Ballasts are especially beneficial for growers using fluorescent lighting systems.

Timer 

Finally, unless you want to manually operate your hydroponic lighting system, you’ll need a timer to ensure lights turn on and off appropriately. For some systems, this is as simple as the type of timer most people use for Christmas lights. For others, it’s as complex as a computer system that adjusts the lighting on the fly to ensure optimal conditions.

Positioning Lights in Hydroponics 

Once you’ve purchased your lighting components, you’ll need to determine the best positioning for your hydroponic lights. 

Determining the Optimal Distance 

First, you’ll need to decide how far your lights should be from the plants you’re growing. Too close, and your plants will burn. Too far away, and they’ll wilt. 

The distance needed between your grow lights and your plants will vary greatly depending on the type of lighting setup you’ve chosen. If you’ve purchased grow lights specifically designed for the purpose, look for the manufacturer’s recommendations on optimal lighting distance. If you’ve created your own system, some trial and error may be involved.

Generally, starting your lights around 12 inches above your plants is best. Watch your crops closely for their response, then adjust your lighting up or down as necessary until you get the correct positioning for optimal plant health.  

Adjusting Light Position Over Time 

Remember that most plants will grow taller with time. Your lights should be moved higher over time as well. If your plants thrive with your hydroponic lighting system around 18 inches above your plants, you’ll need to maintain that distance as your plants grow.

Frequently Asked Questions (FAQs)

We've answered a few of our most frequently asked questions about hydroponic lighting to help you get started:

What light is best for hydroponics? 

The best hydroponic lighting option is a system of LED grow lights that emit both warm and cool spectrums, along with a computerized timer that can simulate daily solar patterns for the appropriate season and climate for your plants.

Are LED lights good for hydroponics? 

Most growers agree that LEDs are an excellent choice for your hydroponic lighting system. LED lighting systems, especially specialized grow lights, may be more expensive up front than some options but are also longer lasting, meaning they will cost less over time. LEDs can provide bright light with minimal heat output and less energy consumption than other options.

Can you use any light for hydroponics?

Technically, you can use just about any light for your hydroponic system, but some lighting types produce healthier plants than others. Older incandescent bulbs were generally considered the worst option for plants as they produced very little blue spectrum light while putting out a lot of heat. Today’s household LEDs are a far better option, but specially designed grow lights offer the best hydroponic lighting benefits.

How far should LED lights be from plants?

The correct distance depends on the type and design of your LED lights. Wattage, reflectors, and other factors will make a great deal of difference. If you’ve purchased grow lights, there should be information from the manufacturer on how far from your plants to place the lights. If you’ve custom-designed your lighting system or are repurposing LEDs not designed as grow lights, start by placing them at least a foot above the tallest plant, then carefully watch your plants and adjust as needed.

What color light is best for hydroponics?

Plants need different color spectrums for different stages of plant development. You will need both warm and cool colored lights to ensure your plants are as healthy as possible. Cool-colored lights in the 400-520 nm range are essential for plant growth, while warmer lights in the 610-720 nm range will help your plants flower and bud. 

We hope this page has provided a better understanding of hydroponic lighting and its importance in indoor farming. If you're interested in learning more about hydroponic produce and how Eden Green Technologies is using Innovative Hydroponic Systems to revolutionize agriculture, stay on our website for a while.

For more information on Hydroponic Technology and Food, please visit some of the following pages:

• What Is Hydroponics?

• The Benefits of Hydroponics

• Differences Between Aeroponics and Hydroponics

• How We’re Growing Hydroponics Produce for Retailers

Are you an institutional investor or a VP of Produce looking to invest in sustainable farming methods? Contact us today to learn how Eden Green Technologies can help you achieve your goals.