Indoor Garden Hydroponic Lighting Basics

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Hydroponic indoor gardening is a great way to grow year round no matter your geographic location. Choosing the optimal lighting for your system can be daunting for any hydroponics beginner. With so many options, the truth is the is no one right way. Don’t worry we’ve got you covered here on a good basic overview so you have all the information you need to choose the best lights for your hydroponic system for success.

Why Do Hydroponic Systems Need Lighting Systems?

The Basics of Hydroponics Lighting

The Basics of Hydroponics Lighting Explained

With outdoor growing such as in a garden, we don’t always think so specifically about light because we rely upon the sun. Plants growing in outdoor gardens require about 4-8 hours of direct sunlight per day, and 4-10 hours of indirect sunlight, and 10-12 hours of darkness depending on the type of plant.

Hydroponics systems aim to imitate this with artificial lighting set-ups. All plants require light, from the sun or artificially, to grow and produce flowers and fruit as well as disease control. In many ways, artificial lighting is a superior option. Hydroponics lights are easily customized to suit plant growth, giving them just the amount of light they need without being dependent on the weather.

How Do I Choose The Best Grow Lights For Your Indoor Garden

Before you decide which lighting system to buy, you need to be clear on which types of hydroponic systems you are going to be using. So much depends on the hydroponics system, how big it is, what plants you are growing, and your goals. You won’t be able to choose the best artificial light source until you are sure of this information. If you’re still deciding which hydroponics system to use, here’s a great guide on how to start a hydroponic garden and the basics of how each different type works.

The items to consider before deciding on a hydroponics lighting system:

Full Spectrum vs. Partial Spectrum Lights

Full Spectrum vs. Partial Spectrum Lights

As you learn more about lights for the span of your plant’s life, you’ll probably notice them being referred to as partial or full-spectrum types. This classification refers to the color temperature of each bulb. Temperature doesn’t refer to heat, but to which side of the solar color the bulb is replicated. These lighting options produce all wavelengths of light, like a rainbow. They mimic natural sunlight, providing a wider range in the necessary proportions for optimal plant growth. Partial spectrum options lean towards one color. Compact Fluorescent Tubebulbs give off light mostly blue, while incandescent lightbulbs primarily emit light in the red range.

To thrive, most plants need light from all spectrums. While a seedling is growing up and producing foliage, it specifically needs blue color light. During the flowering or fruiting stage, a vegetable plant must have light in the red range. Full-spectrum lighting options provide this all-in-one, while other lighting systems may require purchasing different types of bulbs to cover the plant’s full growth.

The Components of Hydroponic Lighting Systems

To understand what you need, first, you’ll need to have some basic knowledge about what parts make up a lighting system.

Bulbs – There are three main types of bulbs, Compact Fluorescent (CFL), Light-Emitting Diode (LED), and High-Intensity Discharge (HID), which includes both Metal Halide (MH) and High-Pressure Sodium (HPS) lights.

  • Compact Fluorescent: These bulbs are inexpensive, energy-efficient, and produce low amounts of heat. Fluorescent lighting is best for quick-growing vegetables that don’t want a lot of heat output, like lettuce, herbs, and spinach. They are not very powerful and aren’t a good choice for fruiting or flowering plants that need high output. Fluorescent lights are an easy, accessible, and economical choice. Recently, a new T5 fluorescent grow light has become available, which offers a broader light output as well, so you don’t need to purchase as many bulbs. One of the greatest things about fluorescent lighting is that they screw into regular light sockets, making them super easy to incorporate.
  • LED Lights: The next most popular option full of advantages. They are the most energy-efficient option, LED’s last a long time and provide full-spectrum low heat. LED grow lights adaptable wavelengths, making them the ideal choice for beginning growers. Long lifespan any LED bulbs will last between 50,000-80,000 hours. Energy efficient consuming about 60% less energy than other options running cooler as well which is cost-saving in two ways. If you decide to use LED grow lights, look for options with a switch that lets you toggle between vegetative and bloom selections.
  • HID: The most common option for hydroponics systems before LED’s became available, HID lights are excellent for all the growth stages of plants. They are powerful, high output, full-spectrum, and useful for growing foliage and for fruiting or flowering plants. Unfortunately, they are inefficient, require large amounts of electricity, and the bulbs wear down fast. HID lights also put out a lot of heat and require the use of cooling fans. There are two main types of HID bulbs. Metal Halide (MH) type bulbs produce blue light, which is used for vegetative growth. High-Pressure Sodium bulbs (HPS) give off more red light and are used to produce flowers and fruit. Generally, MH, Metal Halide and HPS, High-Pressure Sodium bulbs are used together. MH bulbs cost around $200 and last for 1-2 years, while HPS bulbs average $400 and last up to 5 years.

Timer – The ‘heart’ of all the hydroponics lighting systems, the timer keeps the grow lights operating on a schedule. Without a timer, this would need to be done manually, which is extremely time-consuming. Timers are either mechanical or digital.

  • Mechanical timers: Dials or switches adjust time with a simple 24-hour cycle. They usually offer options for 10-15 minute cycles, but other than that, there aren’t many possible adjustments. Mechanical timers are great for small-scale grow rooms and with certain types of hydroponic systems.
  • Digital timers: A little more expensive, but not by much, the digital timer has lots of built-in functions and an easy to read LCD screen. Digital timers allow for complicated daily and weekly schedules, giving the gardener more flexibility. These timers usually come with a battery back-up in case the power goes out. This is extremely important. If you’re not home and there is an issue with the power, your entire indoor gardening operation may suffer.

Reflector Hood – This is the reflective casing around the bulb that focuses the light downwards. Reflector hoods allow the light to spread more effectively and efficiently. Using a reflector hood saves on electricity costs and cooling expenses. LEDs don’t need a reflector hood because their light output is already focused downwards. However, many people do use reflector hoods with their LEDs to increase efficiency. HPS bulbs and halide bulbs benefit greatly from reflector hoods, as the artificial light is better concentrated on the plants, and there is less waste. With halide bulbs, wasted light means higher electricity bills! CFL lighting should always use a reflector hood since they already produce less heat, and plants necessitate a reliable and concentrated heat source for optimal growth. Lightbulbs without reflector hoods are a potentially huge money drain for hydroponics growers. All that energy and heat go to waste when the bulbs give off half their output to the ceiling!

Remote Ballast – The ballast manages the distribution of energy through the light fixtures. For home growers, this is likely a new concept. When you have a multitude of lights operating daily, the basic lightbulb and light switch aren’t going to be sufficient to manage all the power. High-Intensity Discharge lights (HID) need a ballast. CFL light options may require a ballast, but usually, the ballast is integrated into the lightbulb. LED lighting doesn’t need a ballast, but some are ballast-compatible, so they can be integrated into an already set-up indoor grow system. The ballast must match the lightbulb wattage, so it is best to purchase them together.

What & How Many Lights
Do I Need For My Hydroponics System?

The type of lighting you need depends on what you are growing and the size of your hydroponics set-up. Compact Hydroponic Full Spectrum lights are ideal for growing leafy vegetables and plants, like herbs and salad greens. All other plants benefit from a broad range lighting system, with full-spectrum light.

An essential part of choosing lights is to first figure out how many you need. The number of bulbs you need may influence which lighting types you buy. For example, if it turns out you need 20 light fixtures to cover your hydroponics set-up adequately, it may be too expensive to use all led lighting. Metal Halide bulbs or HPS bulbs may be the better investment per watt for your plants.

First, you’ll need to draw up a basic diagram of your grow room to determine the best lighting option. When grow lights are placed over your plants, they create a ‘footprint.’ The footprint is simply the area that the light shines. It is determined by how high up the light is from the plants, and it’s brightness. If a plant isn’t getting adequate light, it will not grow as well, so figuring out the footprint of your bulbs is extremely important. Also, once you figure out how many bulbs you need, you can determine the projected cost of each type for your project. These are just a few of the basics to consider when organizing and planning the light source for your hydroponic system. While you are doing this, be sure to base the footprint on the space the plants will occupy, not the actual grow room size. The plant’s foliage will take up less space than the actual room; you don’t need to light-up the entire grow room.

As you analyze the bulb intensity footprint, keep these specifications in mind: HIDs are best hung 24-36″ above the plants, fluorescent lighting can be as low as 5″, and LEDs are ideal between 5-20″ above the vegetables.

It is possible for plants to get too much light, so plan the set-up carefully. Hydroponic system lighting arrangements often provide too much intense heat, and plants end up stunted, light bleached, or burned. All lighting systems should have adjustable heights to mitigate this issue.

Basic Hydroponic Light Blueprint Guide

Plants need an average of 30-60 watts of light per square foot. This varies with types of plants and where they are in the grow cycle. Many newer bulbs list the average footprint on the packaging, making it easier to choose the right ones. However, the accuracy of this number is highly dependent on the manufacturer, and it is common that they are not entirely correct.

Basic Hydroponic Light Blueprint Guide

CFL Bulbs

All fluorescent bulbs list the actual wattage and an incandescent equivalent.​ It may look something like this: 23 Watt Energy Smart – 100 Watt Replacement. The important number is the actual wattage. The highest wattage compact fluorescent is 105W. The general rule of thumb is if you need more than 250 watts of light, use other bulbs because the fluorescents are inefficient by that point.

These bulbs come rated on the Kelvin scale, which indicates how warm or cold it is on the color spectrum. Choose lower Kelvin ratings (2700K) for the fruiting and flowering and higher ratings (6500K) for vegetative growth.

If you have a 2- square foot space to light, you’ll need 5-6 of the 23 Watt actual wattage bulbs to get 60 watts per square foot. This gets confusing since the bulb says it equals 100W, but that equivalent number should be ignored when determining the needs of the plants.

How we arrived at this number:

The goal is 60 watts per square foot. There are 2 square feet. 2 square feet x 60 watts = 120 watts total need. Each bulb is 23 watts. 120 total watts needed divided by 23 = 5.21 (round up to 6). This space needs at least 6 of these bulbs to reach lighting requirements.

HPS and MH Bulbs

To determine how many bulbs you need, divide the useable grow space by square feet. For example, a 100 square foot space could be lit with four 1000 watt bulbs (100 divided by 25 square feet = 4) or twenty-five 150 watt bulbs (100 divided by 4 square feet = 25). The 600 watt and 1000 watt bulbs are the most efficient, so choose those when possible.

  • 150 watt: 2 x 2 feet (or 4 square feet)
  • 250 watt: 2.5 x 2.5 feet (or 6.25 square feet)
  • 400 watt: 3 x 3 feet (or 9 square feet)
  • 600 watt: 4 x 4 feet (or 16 square feet)
  • 1000 watt: 5 x 5 feet (or 25 square feet)

To determine how many HID bulbs you need for your grow space, here’s a great calculator to determine coverage.


Divide the grow space by square feet, as with HPS and MH bulbs. A 100 square foot space can use four 1000 watt bulbs, six (or seven) 600 watt bulbs, or eight 400 watt bulbs.

  • 200 watt: 2 x 2 feet (or 4 square feet) [at 16″ above plants]
  • 400 watt: 3 x 4 feet (or 12 square feet) [at 16-24″ above plants]
  • 600 watt: 4×4 feet (or 16 square feet) [at 24″ above plants]
  • 1000 watt: 5×5 feet (or 25 square feet) [at 24″ above plants]

This calculator is an excellent resource for determining how many LEDs are needed, based on low, medium, and high lighting levels.

Choosing lights for your hydroponic system looks complicated, but that’s only because each grow space is so unique. Once you figure out the basics of your hydroponics set-up, especially the square footage, deciding becomes much simpler. Then, it’s just a matter of figuring out how many you need based and what fits in your budget. For the beginner, it’s best not to overthink it. Start small. One of the greatest things about hydroponics is the systems are almost always easy to expand incrementally, making it easy to start small and build up as desired.

*Keep in mind to give you the most all-inclusive content possible and how-to guides that we may occasionally use affiliate links in which we receive commissions when you click the links and make purchases. However, this does not impact our content or establish bias. We try our best to keep things as informational as possible in order to help you grown the plants, flowers, herbs and vegetables of your dreams.

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