Types of grow lights

Grow Lights

The natural light from a window is seldom enough for good, strong seedling growth. They will usually stretch and lean towards the light and will not produce sturdy plants. Sowing seeds indoors under fluorescent lights is the easiest way for the home gardener to control growing conditions and grow healthy transplants. Incandescent bulbs give off more heat and less light (mostly red) than fluorescent tubes and will not produce good transplants by themselves.

Many gardeners use inexpensive and widely available “shop lights”– 4-ft. long lightweight metal fluorescent fixtures that take two T-8 fluorescent tubes (multiply the T-number X 1/8 inches to get tube diameter; in this case 8/8 or 1 inch). T-8 fixtures and tubes have largely replaced and are more energy efficient than T-12 fixtures and tubes. You can hang these fixtures by removing the strip or panel above the tubes and inserting chain or wire through the hole(s) in the top of the fixture.

T-5 fluorescent fixtures and tubes are another option. They are relatively expensive, but typically allow for more rapid and robust plant growth. Unlike T-8 tubes, the T-5 tubes can’t be used in a T-12 fixture (common shop light).

Light Stands

Chlorophyll absorbs most of its energy from the violet-blue and orange-red wavelengths. Cool, white tubes (40 watts) produce light in the blue and yellow-green segments of the light spectrum. They are the least expensive and the mostly blue light can produce healthy, stocky salad greens and vegetable transplants. The more expensive full-spectrum fluorescent tubes (“grow lights”) produce a balance of warm (red) and cool (blue) light. “Grow lights” enhance foliar growth and produce thicker stems than cool white tubes, and are needed for producing flowers on indoor plants. Some gardeners insert one warm and one cool tube into a fixture to gain the same effect.

See also: DIY PVC table-top light stand (photos and step-by-step instructions) and growing transplants indoors.

Comparing Fluorescent Lights

*Lumens measures light intensity over the visual spectrum- the brightness that we see.
** Over time the bulbs begin to lose their intensity. T-8 bulbs have a slower period of decrease,losing about 10% of initial brightness after 7,000 hours. T-12 bulbs can lose 20% after the same number of hours.

What Are Grow Lights: Tips On Using Grow Lights On Plants

What are grow lights? The easy answer is that grow lights act as sunlight substitutes for growing plants indoors. There many types of grow lights and using grow lights on plants can be very simple or extremely complicated. Read on for basic information to get you started.

Types of Grow Lights

Fluorescent Tubes – Because they are inexpensive, easy to use and readily available in a variety of sizes and shapes, fluorescent grow lights are the first choice for many home gardeners. Fluorescent lights, which provide light primarily on the blue end of the spectrum, are cool to the touch, so they are safe to use above tender seedlings. Compact fluorescent lights are great for small-space gardening. You can also use newer full-spectrum fluorescent grow lights which, because they provide light on the both ends of the spectrum, are very close to natural daylight.

LED Grow Lights – This new technology offers many benefits to indoor growers and greenhouse owners because they are compact, low-heat, lightweight and easy to mount. LED lights may appear dim to human eyes because the bulbs don’t provide a lot of yellow-green light, but they offer plenty of red and blue light that maximizes plant growth.

Incandescent Lights – Old-fashioned incandescent lights are hot and can’t be placed too close to tender plants. However, some gardeners use incandescent lights, which provide light only on the red end of the spectrum, to supplement standard fluorescent tubes that provide mostly blue light. However, most indoor growers are opting for newer technology LED or fluorescent lights, which are easier to use and more energy efficient.

Other types of indoor lights include metal halide lights or high pressure sodium lights.

Using Grow Lights on Plants

Selecting grow lights for plants requires careful consideration, as plants have very different lighting requirements. For example, plants such as dracaena or ferns require lower light while African violets and similar plants thrive in low to moderate light.

In general, succulents, most herbs and many types of orchids need more intense light. Seedlings require a lot of bright light to prevent them from becoming leggy.

Keep in mind that nearly all plants need at least six hours of darkness. An inexpensive timer will simplify the process.

1.  Fluorescent Grow Lights

If you’re just starting out with indoor growing, you can understand how hard it is to wrap your head around the complexities of grow lights. Hopefully, this guide will help you to make the right choice in different types of grow lights.

Every grow light has a specific use and can vary greatly in terms of their benefits and disadvantages. That is why you should know about the different types of grow lights that you can find on the market:

Table of contents

Fluorescent grow lights are very popular in the grow light market. This type of grow ligt is quite different from regular household grow lights because their tubes are usually calibrated by diameter with the ‘T’ representing 1/8th of an inch.

For instance, T5 means 5/8th of an inch. Fluorescent grow lights are cooler than other grow lights, making them ideal for the propagation phase of your crops.

Pros

  • Covers a large surface area
  • Affordable
  • Long-lasting
  • They don’t use a lot of electricity
  • Good choice for short spaces

Cons

  • Not ideal for flowering and vegetative phases
  • Smaller yields per watt than other types of lights

2. High-Intensity Discharge (HID) Grow Lights

Let’s talk about some other types of grow lights: HID grow lights involve large huge bulb systems that produce light through ignition within the bulb. There are three different types of HID grow lights: high-pressure sodium (HPS), metal halides (MH) and hybrids of the first two.

HID grow lights use dual tungsten electrodes that arc an electric current between them to ignite the gas in the bulbs. HID systems include a bulb, ballast and reflective cover, which altogether increase the light supply to different gardens

Pros

  • Adjustable lighting
  • More light intensity than fluorescent lights
  • Can be used without ballast replacements
  • Most efficient type of grow light (highest yield per watt)

Cons

  • Can burn plants
  • Require replacements over time
  • HID bulbs produce a lot of heat
  • Require additional equipment like the reflector and ballast

3. Double-ended (DE) Grow Lights

DE grow lights are another kind of HPS lights that connect to each end of a ballast instead of to just one ballast port. While a single-ended light loses efficiency after 10,000 hours of use, DE lights maintain 90% percent efficiency with the same usage. DE lights are also slimmer than single-ended ones so that more light is provided.

Pros

  • Efficient
  • Slim design

Cons

  • Can burn plants
  • Efficiency is reduced through nitrogen contact

4. Ceramic Metal Halide (CMH)/Light Emitting Ceramics (LEC)

CMH and LEC lights belong to the single-ended category. They can be substituted with each other since they come from the same family.

LECs and CMHs comprise of a ceramic element to give a higher intensity of light that can actually mimic natural sunlight. The addition of insulation also ensures control of the heat output so that crops aren’t burned. LEC lights are able to produce enough light to support vegetative and flowering stages, which is a great plus.

Pros

  • Longer-lasting than DE lights
  • Mimics natural sunlight
  • Supports all growth stages

Cons

  • Only uses magnetic ballasts
  • Expensive
  • High UV ray exposure
  • Produce a lot of heat

5. Light-Emitting Diode (LED) Grow Lights

LED grow lights are part of the newest grow light technology introduced to the world. LEDs are able to produce more light per watt compared to other conventional kinds of grow lights. They are energy-efficient since they conserve power even over long hours of usage every day. LEDs work at cooler temperatures so burning of crops and gardens is avoided as well.

While LED lights have higher initial costs than other grow lights, they make up for it with better efficiency, growth, energy consumption and maintenance.

Pros

  • Energy-efficient
  • Lowest power costs of all the grow light types
  • Long-lasting
  • Better long-term investment
  • Higher light production
  • Large range of the light spectrum
  • Often adjustable light for each stage of plant growth
  • Easy to use
  • Does not need frequent replacements
  • Small lights can be used without any additional equipment (plug and play)

Cons

  • Larger investment than other grow lights
  • Does not efficiently help in the flowering phase
  • Sometimes needs additional equipment including reflectors
  • Although cooler than most lights, LED still produces heat. Especially with larger lights you will need additional equipment
  • On average these lights have a slightly smaller yield per watt than HPS grow lights

Summing up the different types of grow lights

There are different types of grow lights out there and every type has its pros and cons. For small growers (1/2 to 1 ounce of Cannabis per month), LEDs will definitely be your best choice. If you are a bigger grower you should definitely look into the newest models of LED grow lights. Older LED grow models will not outperform HPS grow lights. Nowadays all the new LED grow light models outperform the HPS because they often don’t need extra setup and are super low on electricity.

Further Reading

Check out our complete guide on buying the best LED grow light for indoor growing.

Check out all of our reviews right here and read all our informative articles right here.

SummaryArticle Name The Different Types of Grow Lights Description Learn about all the different types of grow lights. We tell you about all the pros and cons of the different options to grow your plants. Author GrowYour420 Publisher Name GrowYour420 Publisher Logo

Understanding the Different Types of Grow Lights Available

Most indoor growers are aware that plants need different types of light for good growth and high yields. We as human beings see light in the wavelengths that comprise the visible spectrum (remember Mr. ROY G BIV?).

Plants use light in this range, but also need the light that occurs at both higher and lower wavelengths: ultraviolet (UV) and microwaves. It is an oversimplification of the concept, but in general, plants need more light from the blue side of the spectrum during their seedling stage and when developing foliage and require light from the orange to red side of the spectrum while in blooming and fruiting phases.

When considering the different types of grow lights available on the market, understanding efficiency, both in energy consumption and photosynthetic benefits, is key. Knowing the difference between different types of grow lights, their features and benefits, as well as their limitations can help the grower to decide which will work best for their growroom set-up and situation.

HPS Grow Lights

High pressure sodium (HPS) lights have been a common choice among indoor growers for many decades and are the most common type of grow light used in the commercial greenhouse industry still.

They emit lights mostly in the yellow to red range of the spectrum, 565-700 nanometers (nm). For reference, yellow light occurs at wavelengths between 560 and 590 nm, orange at wavelengths between 590 and 625 nm, and red at wavelengths between 625 and 700 nm.

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HPS lights usually last for spans of time around 10,000 hours (though bulbs should be changed after 18 months of uses even if they have not been used for the full 10,000 hours as the quality and quantity of light diminishes over time) and burn between 25 and 30 per cent efficiency.

The remaining energy emitted from the bulbs is released as heat, making the surface of these bulbs extremely hot (some studies have shown surface temperatures of HPS lights as high as 842°F).

HPS lights should not be placed in contact or very close to crops as they will burn the foliage. For safety reasons, they should not be in contact with anything flammable such as some types of shade material or paper.

It should also be noted that in most large, commercial growing facilities like greenhouses, they are used as a supplement to the natural light. Growers that opt to use HPS light as the sole source of artificial light are not giving their plants anything useful from the blue range of the spectrum.

HID Grow Lights

High-intensity discharge lights (HID), also known as gas or discharge lights, are commonly manufactured as metal halide (MH) or sodium vapor lights (HPS lights are HID lights, but they are excluded here since they were discussed above). These work by passing electricity through a gas-filled tube.

High-intensity discharge lights offer the brightest light of any lights discussed in this article, so they offer the added benefit of allowing crops to be easily inspected. They were used by growers for many years since they are about 10 times more efficient than traditional incandescent lights, which are inefficient, burn hot, and offer little in the way of blue light.

High-intensity discharge lights, while more efficient than incandescent lights, still emit a lot of heat. Among the HID light choices, HPS lights are roughly equivalent in terms of energy efficiency compared to MH bulbs, but they are more efficient in their photosynthetic value.

Metal halide bulbs offer better light on the blue side of the spectrum than HPS do. High-intensity discharge lights also require large, bulky, and often costly fixtures to operate them, though the bulbs themselves are relatively inexpensive.

They are not typically the grow light of choice for most hobbyist growers or growers who operate in relatively small growrooms. The technology, however, is old by today’s standards and most current research is being directed towards light emitting diodes (LEDs) and sulfur plasma technologies.

If HID lights are a practical or more economically viable solution in a certain situation, a combination of both MH and HPS lights may be advisable if the crops being grown are blooming or fruiting crops as opposed to foliage crops like edible greens. These can be operated at the same time or alternated, depending upon the stage of growth; better results will likely result by using both in tandem.

Though HID bulbs are not interchangeable with one another, conversion lamps have been available for some time, which allows you to achieve the spectral output of an MH lamp in an HPS fixture. Also, there are double-ended MH lamps that have been recently introduced to the market that can be used as a direct replacement in a compatible HPS fixture.

LED Grow Lights

Light emitting diodes have become the grow light of choice for many professional and hobbyist growers alike. These products can emit light in wavelengths ranging from 250 nm to more than 1,000 nm.

Most plants require wavelengths of light ranging from the blue section of the spectrum at about 450 nm to the far-red end of the spectrum at about 730 nm at different times of their development. Light emitting diodes have the capability of having their spectra manipulated to efficiently capture the nuances of the emitted wavelengths.

These lights are also favored because of their long life and efficiency. They have been shown to last more than 50,000 hours, with efficiency usually ranging from a low of 38 per cent to a high of more than 50 per cent.

They are also extremely useful for growers because some LED lights can emit light in specific ranges of wavelengths to support plants during their vegetative and blooming phases. Light emitting diodes do not require the addition of any kind of reflector, as the light is directly emitted towards the plants and not dispersed like other types of grow lights.

A 2014 study conducted by researchers at Purdue University showed that LED lighting was more effective for development of commercially viable bedding plants than HPS lighting. This study included popular annuals such as geraniums, impatiens, petunias, salvia, and others.

The main obstacle for growers is the relative high cost of LEDs. The cost of LEDs, however, is dropping as they continue to be produced in higher volumes by more manufacturers.

A current study released this year in the journal HortScience cites that it still costs five to 10 times as much to set up a new LED grow light system as compared to a new HPS system.

Another drawback of LED lighting is one of its selling points. Because far less light is lost or scattered with LED beams, it is not necessarily the best choice of lighting for larger operations. These lights can be thought of as more surgical while HID lighting is designed for saturation. Small grow operations will likely see more benefit with a switch to LEDs than their larger counterparts.

Sulfur Plasma Grow Lights

Sulfur plasma lights are the new kid on the block in the world of grow lights. Their high cost will keep them out of the hands of the casual grower for a while until market factors kick in based on their effectiveness for supporting plant growth. Many units currently sell for thousands of dollars each.

The amount of peer-reviewed literature on this new technology useful for the layman is scant, so it is difficult to glean an unbiased review of their performance. Of all the possible options in grow lights, the sulfur plasma light is touted to emit light in frequencies and wavelengths closest to that of the sun. It is the only grow light that emits lights via microwaves. Its efficiency has been reported by some European researchers as high as 70 per cent.

More Grow Lighting Tips

Don’t forget about the inverse-square rule when placing your grow lights. The amount of light that is scattered or lost grows exponentially larger the higher the lights are suspended over the crops.

Every time you double the distance between your light source and your plants, they receive one-fourth of the amount of light than when you started. This is important when considering a type of grow light that produces a lot of heat, which needs to be kept away from crops to avoid burning of foliage.

Ultimately, whichever light is chosen for optimal growth, remember that all plants still need a daily period of darkness to complete their normal cycles. The amount of darkness a plant experiences provides cues to the plant regarding when to flower or when to produce vegetative growth. This is known as photoperiodism.

Grow Light Breakdown: Heat, Cost & Yields

by Nebula Haze

For the many growers who are unable to cultivate cannabis outside in the free abundant sunshine, grow lights are necessary to successfully grow cannabis indoors. Grow lights take the place of the sun, and power the growth of your plants and their buds. Light is like “food” for your plants, so without a lot of bright light, even a healthy cannabis plant won’t produce much bud at all.

More Light = Bigger Yields!
(up to a point, it is possible to give your plant too much light!)

3 Main Classes of Marijuana Grow Lights

There are lots of options for grow lights that work well for growing cannabis indoors but in the end they boil down to 3 major types:

1.) Fluorescent Grow Lights

  • Compact Fluorescent Lights (CFLs)
  • T5 grow lights (and other fluorescent tubes)

2.) High Intensity Discharge (HID) Grow Lights

  • Metal Halide (MH)
  • High Pressure Sodium (HPS)
  • Ceramic Metal Halide (CMH, LEC, Light Emitting Ceramic)

3.) LED Grow Lights

  • (LEDs come in a huge variety of sizes and form factors. There aren’t really any “standard” types yet, though some lamps get better results than others.)

Note: Some growers may have heard of “Induction” grow lights, which are pretty rare these days but still pop up from time to time. There are two types: “Magnetic Induction” grow lights do okay for growing cannabis but they’re pretty much glorified fluorescent lights. “Plasma Induction” grow lights actually perform pretty poorly at growing cannabis.

Some types of induction lights are well suited to stadium lighting but honestly they just aren’t that great for growing cannabis and they come with huge price tags. Even a lot of LEDs are cheaper and you’ll get better results with them. You can learn more about induction grow lights here.

Note 2: Incandescent light bulbs (old fashioned light bulbs) are NOT suitable for growing marijuana!

Compare the Pros and Cons of Each Grow Light

1.) Fluorescent Grow Lights

Fluorescent grow lights come in many different shapes and sizes, from twisty bulbs to long tubes. Fluorescents are popular because they make efficient and pleasant lighting for humans, and also work great for herb gardens and other types of low-key indoor gardening without using a lot of electricity.

Read full tutorial on CFL grow lights

Read full tutorial on T5 grow lights

CFL Grow Lights

CFL grow lights are the twisty-looking bulbs you can find anywhere you normally buy light bulbs. They produce a great spectrum for growing cannabis and can be used in tiny spaces where no other grow light would fit such as the inside of a cabinet.

Keeping CFLs close results in the best yields and growth

Learn more about CFLs

T5 Grow Lights

T5 grow lights are one of the most easily available types of grow lights and are used to grow many different types of plants. As a result, they’re available in many garden and home improvement stores.

T5s are much bigger/wider than CFLs and usually come as part of a panel, but they can still be kept mere inches away from your plants without worrying about burning them.

These cannabis plants are thriving under T5 grow lights

Learn more about T5 grow lights

Pros of Fluorescents

  • Cheap to buy
  • They don’t use a lot of electricity or make a lot of heat unless you have a lot of them packed together in a small space
  • Great light spectrum for growing cannabis
  • Since lights can safely be kept just a few inches away from plants, they’re a good choice for short spaces
  • One of the best lights for clones, seedlings and young plants. Big lights must be kept far away from young plants to avoid burning them, which ends up wasting a lot of light and energy. By using smaller lights like fluorescents while plants are still short, you can save quite a bit of money on electricity during those first few weeks compared to using a high-powered grow light.

Cannabis plants under a T5 grow light – when plants are trained (like these ones in a Scrog setup) you can get pretty decent yields from fluorescents.

Read more about CFLs vs T5s

Cons of Fluorescents

  • Fluorescent grow lights get smaller yields per watt than the other types of grow lights if you use them in the flowering stage while buds are forming. With fluorescents you can expect about 0.25 grams of buds for every watt of electricity (using the true watts out the wall, not any type of “equivalent” watts), while LEDs and HPS get 2-4 times as much yield per watt of electricity.
  • The light from a fluorescent lamp doesn’t penetrate far down into the plant so they are best suited to plants that have been trained to grow short and flat; they aren’t powerful enough to support tall plants in the flowering stage.

Example of CFL grow setup which yields up to half ounce per month

Fluorescents are a great choice for clones, young plants, supplemental lighting and can save you money on electricity in the vegetative stage compared to using high power lights when plants are too young to use it all anyway. They can also be used to flower plants in spaces that are shorter than what’s possible with other grow lights (aka ‘stealth growing’).

That being said, when it comes to the flowering/budding stage, if you can fit a bigger light you will get significantly better yields/watt by using an HID or LED grow light!

Learn more about T5 grow lights

Learn more about CFLs

You might be interested… More on CFLs vs T5s

2.) High Intensity Discharge (HID) Grow Lights

HID grow lights are much more efficient than fluorescent lights and are powered by large, oddly-shaped bulbs. They are usually screwed into a reflector or hood to reflect more light down onto the plants. HIDs are great at growing cannabis, but they also get very hot and are usually hooked up to an exhaust to help vent out heat.

Full tutorial on MH & HPS grow lights
(most common grow light combination for cannabis)

Full tutorial on CMH / LEC grow lights
(LEC stands for “Light Emitting Ceramic” and is a type of Metal Halide bulb that is built with ceramic like an HPS – basically it’s sort of like a blend between MH and HPS bulbs)

Metal Halide (MH) Grow Lights

Metal Halide grow lights are generally used for the vegetative stage because they produce a bluish light that vegetative plants love, though this type of light can also be used all the way to harvest.

The light from a Metal Halide appears a little bluish, and is well suited to growing cannabis plants in the vegetative stage

Learn more about MH grow lights

High Pressure Sodium (HPS) Grow Lights

High Pressure Sodium grow lights are often used during the flowering stage because they are very efficient and their yellow light stimulates bud production. HPS grow lights in the flowering stage get better yields per watt of electricity than any other type of grow light available today, which is a big part of why they are so popular.

The light from an HPS appears yellow, and is great for flowering plants because the light spectrum stimulates bud production

Learn more about HPS Grow Lights

Ceramic Metal Halide (CMH) & Light Emitting Ceramic (LEC) Grow Lights

These are actually just two names for the same thing. This type of metal halide bulb uses ceramic as part of the lamp just like an HPS. As a result, CMH bulbs are more efficient than regular MH lights (though still not as efficient as HPS bulbs).

“LEC” and “CMH” both refer to Ceramic Metal Halide grow lights, which is a type of HID light that is a bit more efficient than a regular Metal Halide light

Learn more about CMH / LEC grow lights

Pros and Cons of HID Grow Lights

Pros

  • HIDs are the most efficient type of grow light (gets the highest yields/watt).
  • Of all the HIDs, HPS grow lights are the most efficient and the best for the flowering stage. When using HPS grow lights in the flowering stage, you can expect about 0.5-1 gram/watt if all goes well.
  • HID lights are simple to use because they can be hung the right distance from the plants with no guesswork on your part (unlike LEDs), and no need to adjust the lights all the time (like fluorescents).

Cons

  • HID bulbs get really hot and generate a lot of heat. Because of the concentrated heat production, you will almost always want to put the bulb in a hood and also provide some sort of cooling to prevent heat from beaming down onto your plants and driving up the ambient temperature of your tent/grow room. This is especially important for the bigger lights with power above 250W.
  • Additional setup – As a result of the heat mentioned above, most growers use an exhaust fan with ducting to vent out heat. Unfortunately, the prospect of having to deal with the fan and ducting scares off many growers from HID lighting.
  • More parts – HID lighting means a few more parts than other types of lighting. Fluorescents are just the bulb and a fixture and most LEDs are just the light itself. But most HID setups have at least a bulb, fixture, an external ballast and an extra cable if you don’t count the exhaust systems parts, too.

Example of MH/HPS Setups That Yield 1-5 Ounces/Month

250W HID

  • 1-2 oz per month
  • Electricity: $69/month (including electricity for fans)
  • Initial Setup Cost: $605.00

400W HID

  • 1.5 – 3.5 oz per month
  • Electricity: $96/month (including electricity for fans)
  • Initial Setup Cost: $744.00

600W HID

  • 2.5 – 5 oz per month
  • Electricity: $128/month (including electricity for fans)
  • Initial Setup Cost: $780.00

There is a larger size MH/HPS grow light available (1000W), but at that size it starts going outside the scope of a “hobbyist” grower as far as ease and yields. In addition to needing a lot of extra cooling which costs electricity, a 1000W HPS grow light is less efficient compared to a 600W grow light (as far as how much light is put out for electricity used). I think most hobbyist growers would be happier with a 600W, or even two 600W lights, over a 1000W 🙂

HIDs are very well suited to growing cannabis and very easy to use once they’re set up. If your main goal is to get the highest yields possible, then HIDs are the way to go! However, they do require extra setup compared to the other grow lights because chances are you will need a fan to vent out heat from your grow space.

Learn more about MH / HPS grow lights

Learn more about CMH / LEC grow lights

3.) LED Grow Lights

LED grow lights are very popular among cannabis growers as an alternative to HPS grow lights. They tend to run cooler and also usually come with built-in cooling. They can often be plugged into a wall and simply hung over plants which is definitely easier than setting up an HID grow light. LEDs also have great penetration so they don’t need to be moved frequently like fluorescents.

Simply hang an LED light over your plants and start growing!

Learn more about growing cannabis with LED grow lights

You might be interested: 5 Barriers to Total LED Grow Light Domination!

Pros

  • LEDs almost always have built-in cooling that pushes heat up and away from the plants (unlike HID bulbs which beam heat down on your plants and need to be cooled separately). As a result LEDs run very cool and many growers are able to get away without venting heat at all.
  • The smaller size LEDs can be plugged directly into the wall and hung up over your plant, without needing to do anything else. You can just plug them in and start growing!
  • Some growers believe LEDs produce more resinous bud. Combining LEDs with HPS grow lights seems to be getting some growers really great results, though more testing is needed.

Cons

  • Although the LED lamp itself usually does run a lot cooler than a similar wattage HPS bulb, they still produce heat and the bigger sizes like 300W+ may need to be vented with an exhaust fan to prevent the grow space from getting too warm.
  • Despite what some sellers may tell you, LEDs get slightly smaller yields per watt than HPS grow lights on average (LEDs commonly yield about 0.5g/watt, though some growers and lamps get better results than others!). There is a learning curve when it comes to getting the best yields from your LEDs, partly because each lamp is different and there are no “standards” to go by yet. A little experience with a specific lamp can improve your yields by a lot!
  • LED grow lights tend to need a lot of space between the lamp and your plants, which means you need a tall grow space to get the best results. This is actually the main thing holding me back from trying LEDs more. Smaller LED panels should be kept 18″ or more away during the second half of the flowering stage to avoid light burning your buds (buds can be burned from too much light even if the temperature is cool), and some of the bigger models need to be kept 30″ or more away from the buds. When in doubt, contact the manufacturer!

If you get very high-wattage LEDs, you may need to vent out heat to keep the grow space cool

For growers who are looking to harvest 1/2 to 1 ounce of cannabis a month, LEDs may be your best choice. At this size, they are super low on electricity, run cool and need almost no setup! They get better yields than fluorescents but don’t run as hot as an HPS of similar wattage.

Here’s an example of a cheap starter LED setup that yields several ounces at harvest every few months

Example of an LED setup that uses a mid-sized Quantum Board (highly recommended!)

Note: When shopping for LEDs, make sure they contain some amount of green or white (full spectrum) light. Plants grown without at least a tiny amount of green or white light are very prone to nutrient deficiencies and simply don’t grow as well. Learn more about how light spectrums affect cannabis growth!

Learn more about growing cannabis with LED grow lights

You might be interested: 5 Barriers to Total LED Grow Light Domination!

Now that you are familiar with all the most common cannabis grow lights I hope your choice is a little easier. I wish I’d had this information when I first started growing indoors 🙂 Happy growing!!!

~Nebula Haze

Ready to learn more? How to increase….

  • Yields
  • Bud Quality
  • THC Levels
  • CBD Levels
  • Smell/Taste
  • Density
  • Bonus: What Determines Yields?

Grow Lights for Indoor Plants and Indoor Gardening: An Overview

Yet unless you’re lucky enough to have a solarium or greenhouse attached to your home, providing sufficient light to your plants will likely be an obstacle (shade-tolerant houseplants excepted). South-facing windows may provide enough light for a tray or two of seedlings, but if you want to grow vegetables, or any other sun-loving plants, to maturity, you’re going to need grow lights.

The indoor lighting found in most homes does little to support photosynthesis. Traditional incandescent bulbs do not have the proper spectrum of light, or intensity, to supplant the sun. Household fluorescent bulbs can make effective grow lights, but only if they are placed in within a few inches of the foliage and left on for 16 hours per day – not ideal.

Warm vs Cool: Understanding Color Spectrum in Grow Lights

When shopping for grow lights, you’ll notice they are labeled with numbers like 2700K or 4000K. This refers to their relative warmth or coolness on the color spectrum – the higher the number, the cooler the light. Foliage growth is generally best around 6500K, though many plants need a period of warmer light, around 3000K, in order to produce flowers, and thus fruit.

In other words, if your goal is to simply produce seedlings, leafy green vegetables, or root crops, you only need higher spectrum bulbs. If you want to grow flowers, marijuana, or any fruiting plant (cucumbers, tomatoes, peppers, lemons, etc.), you’ll also require low spectrum bulbs. You can some types of bulbs are available in full-spectrum form, however, simplifying things.

There are three main types of grow lights.

Full-spectrum fluorescent lights – either of the tube or standard CFL variety – are a great choice when starting seeds indoors. PHOTO: By Falcona / .com

The standard fluorescent bulb, commonly denoted T12, makes a decent grow light for houseplants, starting seeds, supplementing the natural light of a window, and other situations where lighting needs are modest. They are fairly weak in light intensity, however, and must be placed within a few inches of the foliage to have much of an effect.

T5 fluorescent bulbs, which are narrower in diameter than T12s (but still widely available wherever lightbulbs are sold), have a much higher light intensity, making them suitable as a sole light source for sun-loving plants. Compact fluorescent bulbs (CFLs) are an option for small spaces, or if you don’t like the look of long rectangular fluorescent light fixtures – CFLs will screw into an ordinary incandescent light fixture.

Look for specialized full-spectrum fluorescent grow bulbs (like this T5 option, or this CFL option, which fits into a standard socket) to provide the right balance of light for flowering plants.

While they are considerably more expensive than fluorescent bulbs, LEDs use half the electricity and last five times longer, more than paying for themselves in the long run. The average LED bulb from the hardware store is not designed for plant growth, however – you need special LED grow bulbs, a relatively new technology that is increasingly available from horticultural suppliers.

LED grow bulbs are capable of much greater light intensity than fluorescent bulbs and are available in full-spectrum form. An easy rule of thumb: Fluorescent bulbs are often used when growing just a handful of plants; LEDs are preferable for larger quantities since you can achieve higher light intensity per square foot. Another advantage of LEDs? They produce very little heat compared to other bulbs – an issue that can become problematic when you have a lot of lights in a small space.

Before the advent of LED grow lights, HID (high-intensity discharge) lights were the main option for large indoor plantings. They are extremely powerful, but are expensive to purchase, consume electricity inefficiently, require special light fixtures, and give off a lot of heat. All that said, they are very effective and are still widely used. If you want to grow large plants like tomatoes or lemon bushes, HIDs are good bet because the light penetrates farther into the foliage than with other bulbs.

There are two types of HID bulbs. High-pressure sodium (HPS) bulbs are best for flowering (low spectrum), while MH (metal halide) bulbs are required to support vegetative growth (high spectrum); the two types are often used in conjunction. Unfortunately, each type requires its own fixture.

How to Install Grow Lights

Installation requirements vary drastically depending on the scope of your indoor garden and the type of bulb used. But here are a few basic steps to get you started.

Figure out how many bulbs you need.
Most edible plants require at least 30 watts per square foot, but fruiting species (like tomatoes) generally won’t produce abundant high-quality crops without 40 to 50 watts per square foot. Wattage is always indicated on the bulb package. Simply multiply the square footage of your growing area by the number of watts you plan to provide (between 30 and 50); then divide by the number of watts supplied by the bulbs you plan to use.

Devise a light rack.
You’ll need a way to support the bulbs over the plants at the proper height. And unless you’re growing something that will remain at more or less the same height throughout its lifespan, you’ll also need a way to raise the light rack as the plants grow. This is usually accomplished through some sort of pulley system or by hanging the light fixtures with metal chain – that way you can easily adjust the height by changing the link the light fixture is home from. Grow light racks are also available for purchase online.

Add the necessary accoutrements.
It is generally wise to plug your lights into a timer to ensure they get the proper amount of light, and that they get it at the same time each day. Fancy ones are available for indoor growing, though a standard lamp timer also works. If your lights bring the temperature above 80 degrees or so in your growing area, install a ventilation system to prevent heat stress. Aficionados make use of reflectors and all sorts of other grow light accessories to achieve optimum results.

How Long Should I Leave Grow Lights On?

Plants grown indoors require more hours of light than those grown outdoors. 14 to 18 hours of light per day is recommended for most edible species when grown under artificial lighting. Don’t be tempted to leave the lights on 24-7, however – at least six hours of darkness each day is essential to plant health.

As the plants grow, raise the light fixture accordingly to maintain the optimal distance, which varies depending on the type of bulb used and its wattage (the higher the wattage, the farther away the bulb can be). Here are the basic parameters:

Fluorescent Grow Light: 3 to 12 inches

LED Grow Light :12 to 24 inches

HID Grow Light: 24 to 60 inches

Happy planting!

Grow Light

Grow lights or lamps are used when there is not enough sunlight to stimulate plants to grow naturally. This could be due to insufficient outdoor space for a garden, lack of sunlight in winter or other reasons.

Grow lights work in one of two ways. They may be designed to give plants a broad light spectrum that simulates the sun, or they may have a more tailored light spectrum that is designed to cultivate certain plants.

Depending on the type of grow light or lamp, a range of colors is used to mimic specific outdoor conditions, including the sun’s light, color and temperature. A grow light or lamp may be used to cultivate plants when they would otherwise be out of season, so that growers may have a year-round crop. They may also be adjusted and may vary in intensity depending on a given plant’s stage of cultivation.

Plants have different photoperiods (reactions based on time and intensity of light) at different stages of cultivation, and a grow light can be used to imitate sunlight to stimulate those photoperiods and increase the plant’s yield of fruits and vegetables.

Grow lights have been effectively used for plant growth since 1868, when a Russian botanist first began experimenting with the use of artificial light to grow plants. Today, a number of different grow lights or lamps are on the market, including high intensity discharge (HID) lights, metal-halide lights, high-pressure sodium lights, light emitting diodes (LEDs) and others.

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