Indoor Grow Lights

In an indoor garden, grow lights are a critical component. Whatever your level of experience with hydroponics, you’ll need to invest in the correct illumination for your indoor garden. Everything you need to know about …


In an indoor garden, grow lights are a critical component. Whatever your level of experience with hydroponics, you’ll need to invest in the correct illumination for your indoor garden.

Everything you need to know about indoor grow lights will be covered in this post.

Grow lights, in my opinion, are the most crucial item for an indoor garden. Everything else you’ll need to successfully grow plants inside is a waste of time and money without them.

Grow lights are widely misunderstood by the general public, although they may be used in a variety of ways by gardeners of all skill levels. Indoor grow lights can be used in a variety of ways, including:

  • Grow plants from seed to harvest in a greenhouse or indoor grow room
  • In order to get the seeds ready for the upcoming spring growth season.
  • Plants that need more sunlight than the season is offering might be finished off in the garden
  • To successfully root and propagate cuttings
  • In order to extend the growing season for plants that are exposed to sunlight.
  • Microgreens, baby greens, and herbs are all examples of crops that can be harvested at a young age.

There are several factors to consider while purchasing, utilizing, and maintaining for a grow light. With links to more in-depth instructions for certain issues, this article will cover just about everything you need to know about lights.

Important Grow Light Concepts


Having a rudimentary understanding of lighting concepts is helpful before we go any further. The more you know about these, the more equipped you will be to determine which grow lights are most suited for your needs.


All light, both visible and invisible, may be found on a spectrum and is therefore a spectrum. The wavelength of light is measured in nanometers in this spectrum. As indoor growers, we focus on the 400-700 nanometer band of the spectrum, which is known as PAR (Photosynthetically Active Radiation).

PAR refers to the wavelengths of light that plants can employ for all photosynthetic activities, as the name implies. There are sub-bands of light that plants use for specific functions within this band of light:

  • When plants are in the vegetative growth phase, they predominantly use 400-490 nanometers of this “blue” light.
  • 580 to 700 nanometers — This “orange-red” light is utilised by plants during the flowering and fruiting period.

You may be wondering, “What’s the difference between 490nm and 580nm?” “Why aren’t plants taking advantage of that?” What’s more, have you ever pondered why so many plants are colored green? Green light, which happens to be the color you perceive in the 510 to 570nm wavelength range, is absorbed by their choloroplasts.


Plants need light in order to grow, blossom, and produce fruit; now we must determine the amount of light they require. It’s not healthy for your plants if they aren’t getting the correct amount of light!

Intensity is a measure of the amount of light that is emitted. Grow lights can produce a wide range of light intensity based on the type of light you use and how you place your light. A successful indoor grow, therefore, necessitates the correct placing of lights.


Your grow lights’ power consumption is measured in watts. Watts are the unit of power. Various types of grow lights consume drastically varying amounts of electricity.

LED lights, for example, use less power overall than HID lighting. However, this does not imply that LED lights are superior; there are a plethora of other aspects to take into account. ​


This refers to how much space your grow light occupies. It depends on how far away from your plants you set your grow light.

A grow lamp with a large footprint but low intensity is better for your plants if it is placed closer to them. Placement closer to your plants has the opposite effect.

The heat output, intensity, and overall footprint of your grow lights must all be taken into consideration when deciding where to set your lights. With practice, you’ll become more adept at lighting placement.



During a 24-hour period, your plants’ photoperiod determines how much light they receive. You don’t have to rely on the sun to grow plants indoors, so you can keep them lit 24 hours a day if you choose.

For some plants, photoperiod changes are a trigger. The plant senses when it’s time to ripen or flower, and the change is a signal to the plant. A change in photoperiod is required to initiate the flowering phase of growth if you are cultivating this type of plant indoors.

Types of Grow Lights

Let’s have a look at some of the many types of grow lights on the market now that we’ve covered some of the basics of lighting.

It can be difficult to understand this topic because of the convoluted naming conventions and deceptive claims made by lighting companies.

When it comes to choosing the right type for your garden, I aim to shed some light on the various options.

High-Intensity Discharge (HID)

hid bulb

HID lights are a popular choice among growers because of their high light output and affordable price.

Metal Halide (MH)

Metal Halide

During the vegetative phase of a plant’s life cycle, metal halide grow lights are common. This is due to the fact that they emit more light in the blue portion of the spectrum. Plants use significantly more blue light than red light during their vegetative phase.

High Pressure Sodium (HPS)


High pressure sodium grow lights are utilized throughout the growing process, although they are especially popular during the flowering or fruiting stages. They emit a lot of red and orange light, which plants rely on substantially in their latter stages of life. ​

Ceramic Metal Halide​ (CMH)


Ceramic metal halide lamps are among the most intriguing products to hit the market. Although they appear to be a variant of the conventional metal halides, they operate in a quite different manner.

Because of its balanced spectrum output, growers are attracted to ceramic metal halide lamps these days. They have an excellent combination of blue, orange, and red light. As a result, they are a superb “all-around” choice for producers.

They are currently available in 315w and 630w capacities from a few trustworthy manufacturers. The 315w systems often replace a 400w HPS or MH light, thus you save energy while also improving total spectrum output. ​



Fluorescent lighting is widely used in the early stages of a plant’s life cycle. Many amateur and commercial gardeners utilize them to start seeds, root cuttings, and initiate early to mid-stage vegetative development.

They’re incredibly energy efficient, don’t produce a lot of heat, and come in suitable sizes for indoor growers.

While you can make your own configuration using individual CFL bulbs, the industry practice these days is to use T5 fluorescent tubes in a variety of diameters. T8 and T12 bulbs are also available, although they are significantly less efficient and have gone out of favor.

When purchasing T5 lights, you have two options:

How many bulbs do you require?
How long do you intend to keep your fixture?
The number of tubes in a fixture can range from 2 to 16, and the length of the fixture can range from 2′ to 4′.

High Intensity Fluorescent (HO / VHO)

There are two further types of fluorescent tubes. High output (HO) and very high output (VHO) are the same technology, but they produce more light.

They run hotter since they are more powerful, so they must be set further away from your plant canopy to avoid burning.

Light Emitting Diode (LED)​​

led grow lights

LED grow lights were received with much suspicion when they first hit the market for two reasons:

  1. Manufacturers made extraordinary claims about their products’ usefulness and efficiency.
  2. They were a new lighting technique, and traditional indoor growers were skeptical.

LED illumination is now more widely used and is extremely popular among some farmers. LEDs have a few distinct advantages that most other sources of lighting do not have.

For starters, they consume extremely little energy and produce very little heat. This is an important consideration for many growers who do not want to spend a lot of money on continual lighting and do not have the space to deal with a lot of heat output.

They’re also made up of several small diodes, so each diode may be programmed to emit a specific wavelength of light.

Growers custom-build the most sophisticated LED lights using chip on board (COB) LEDs for maximum light output and customizability.



Plasma grow lights are a newcomer to the lighting sector, touting exceptional efficiency claims. In many respects, it reminds me of the early days of LED lighting, when manufacturers made absurd claims in order to sell units.

However, plasma grow lights have some distinct advantages. Plasma lights have a far longer lifespan than HID bulbs and emit a more complete spectrum of light. They also work equally well at lower wattages. They are comparable to ceramic metal halides in many ways.

They are, however, far more expensive. Because they are a relatively new technology that has yet to reach the mass market, costs remain extremely high.

Grow Light Cost Calculator

It is quite straightforward to calculate the cost of running your grow lights:

((Total Wattage x Hours per Day) / 1000) x Cost per Kilowatt Hour x (31 for month, 365 for year)

Additional Grow Light Parts

Reflectors and Hoods

Reflectors and Hoods

Most methods of lighting necessitate the use of grow light reflectors and hoods. As an indoor grower, you want to get the most out of your lights. That is, you do not want to squander light output on regions of the garden where you are not interested.

Maintaining Your Grow Lights

Whatever type of grow light you choose, it’s a good idea to follow a few recommended practices to get the most out of your lights.

These ideas are simple, and they will help you get the most out of your investment in grow lights.

​Cooling and Heating

Heat is a consequence of the production of light. The heat output of different grow lights varies. LEDs, for example, produce very little heat, whereas a 1000w HPS bulb produces a lot.

When growing, you must consider how much heat your light emits and position it far enough away from your plants to avoid burning.

LEDs, followed by fluorescents, should be positioned the closest to your plants as a general rule. HID and plasma lighting should be put as far away as possible. ​

Degradation of Lightbulbs

Over time, all grow light bulbs deteriorate. Some decay more faster than others, depending on the type.

Degradation of HID bulbs

HID bulbs degrade with time, much like any other bulb, but for distinct reasons. When you turn on your HID bulb, the voltage surges far above the regular operating level.

Every time you turn on the light, this pulse causes harm to the bulb. After around 6-12 months, the bulb’s characteristics change substantially, resulting in much lower spectrum output. ​

Degradation of T5 Fluorescent Bulbs

Fluorescent lighting deteriorates at a significantly slower rate than HID lighting. There are several reasons for this, but what you should know is that after 20,000 hours, they normally only lose around 10% of their lumen output.

LED Bulb Deterioration

LED bulbs degrade significantly more slowly than conventional types of lighting. In comparison, an incandescent bulb will decay in 6-9 months what an LED bulb will degrade in 15-20 years. That is a MASSIVE difference.

Most manufacturers rate their LED fixtures as lasting 50,000-100,000 hours before bulbs need to be replaced.

While this is true, the temperature at which the bulbs operate has a significant impact on how rapidly they degrade. The hotter they run, the faster they degrade, causing the 50,000-100,000 hour figures to plummet considerably.

When Should You Replace Your Light Bulbs?

No matter how well you care for your bulbs, you’ll need to replace them from time to time.

As a general rule, you should replace your HPS and MH bulbs after they have degraded by 50%. This is possible using a PAR meter.

This is an unnecessarily complicated technique for some farmers. HID bulbs should be replaced every 6-12 months as a general rule.

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