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growing marijuana with fluorescent lights

Grow Light Breakdown: Heat, Cost & Yields

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:

  • (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.

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

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

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.

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.

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!

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

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

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

Pros and Cons of HID Grow Lights

  • 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).
  • 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

  • 1-2 oz per month
  • Electricity: $69/month (including electricity for fans)
  • Initial Setup Cost: $605.00
  • 1.5 – 3.5 oz per month
  • Electricity: $96/month (including electricity for fans)
  • Initial Setup Cost: $744.00
  • 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.

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!

  • 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.
  • 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.

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!

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.

There many grow lights that work well for growing cannabis indoors, but they boil down to 3 popular types: fluorescents (CFLs, T5s), HIDs (MH, HPS, LEC) and LEDs. Learn the differences so you can pick the best option for your setup!

The Different Types of Lights for Cannabis: Pros and Cons

Learning about the many types of grow lights available can be overwhelming, especially for those new to cannabis cultivation. They all serve the same purpose, but many of them go about it in different ways. To clear up the confusion, we’ll be taking a look at the different types of lighting, and breaking down their pros and cons.

Let’s run through a detailed comparison of the most popular cannabis grow lights.

Contents:

Every cannabis cultivator knows how important proper lighting is when it comes to achieving a successful harvest. Along with nutrition and water, it’s one of the most crucial factors in ensuring healthy growth and bountiful yields.

Although natural sunlight is usually optimal for cannabis growing, many cultivators prefer to grow indoors for various reasons. First, not everyone lives in a climate where outdoor growing is feasible. Second, indoor growing involves timed artificial lighting, giving the grower more control over the vegetative and flowering phases of their cannabis.

With that in mind, we believe exploring the world of cannabis grow lights is more than worth it.

Pros and Cons of Different Cannabis Grow Lights

Today, you can find many different types of grow lights for indoor cultivation. But not all are equal; in fact, there are big differences when it comes to effectiveness and cost. In turn, some grow lights may be better suited for certain types of setups than others.

Let’s take a look at the types of grow lights available, and compare them relative to their pros and cons.

FLUORESCENT (CFL) GROW LIGHTS

CFLs, also known as “compact fluorescent lights”, are some of the most common you’ll see out there. You can get these lights at many places, including home improvement stores and even grocery stores.

FLUORESCENT (CFL) GROW LIGHTS

CFLs, also known as “compact fluorescent lights”, are some of the most common you’ll see out there. You can get these lights at many places, including home improvement stores and even grocery stores.

They are especially suited to small grows, and will be the most affordable starter lights you’ll find. Conveniently, these bulbs have standard sockets so you can use them with any standard light fixture. They do not require any special equipment.

You can find “daylight” CFL bulbs at 6500K or “warm white”, with a more reddish light spectrum, at 2700K. Bulbs with a daylight spectrum are more suitable for the vegetative growth phase, while warmer CFLs are better for the flowering phase.

CFL PROS CFL CONS
Low cost and widely available Low light output (only suitable for growing 1–2 plants)
Easy to set up and use Not optimal for flowering (produces subpar yields)
Good for beginners Tends to have a shorter lifespan than other lights
Available in various wattages and colour temperatures
Uses little electricity, saves energy
Doesn’t get hot
Perfect for clones and seedlings
CFL PROS CFL CONS
Low cost and widely available Low light output (only suitable for growing 1–2 plants)
Easy to set up and use Not optimal for flowering (produces subpar yields)
Good for beginners Tends to have a shorter lifespan than other lights
Available in various wattages and colour temperatures
Uses little electricity, saves energy
Doesn’t get hot
Perfect for clones and seedlings

CFL Cost and Expected Lifespan

A standard 40W CFL bulb will only cost a few bucks. This makes them great starter lights for growers on a budget! It’s a lot of bang for your buck, too, as the expected lifespan for compact fluorescents is about one year.

Yield per CFL

Expect to obtain 0.3 grams per watt (roughly 12 grams per standard light).

HID (MH and HPS) Grow Lights

HID (high-intensity discharge) grow lights are somewhat of a gold standard in the cannabis cultivation industry. Many growers swear by HID lighting and believe that they produce the best and biggest yields.

HID (MH and HPS) Grow Lights

HID (high-intensity discharge) grow lights are somewhat of a gold standard in the cannabis cultivation industry. Many growers swear by HID lighting and believe that they produce the best and biggest yields.

There are two main types of HID lights: MH (metal halide), and HPS (high pressure sodium) lights. The difference between the two is that MH lights produce a “cooler”, blueish light, whereas HPS lights are usually red. This makes MH lights more suitable for the vegetative phase, with HPS lights being better for flowering.

Therefore, most advanced growers use a combination of MH and HPS bulbs for the duration of the process. If, for some reason, you need to choose one type of HID for the entire grow, we would recommend HPS lights. 600W HPS lights are the most popular type. In most cases, you can usually get complete sets that include the bulbs, a ballast, and a reflector.

HID PROS HID CONS
Compared to high-end LEDs, HID grow lights cost less outright They give off intense heat that can spike grow room temps or burn plants
Easy to set up and operate, even for relative beginners You’ll need additional equipment to operate them, including an electronic ballast and reflector
Produces excellent yields HID bulbs degrade over time, and you will have to replace them periodically
Reliable and consistent HID lights are very power-hungry and can significantly increase electricity bills
Options for growth and flowering
HID PROS HID CONS
Compared to high-end LEDs, HID grow lights cost less outright They give off intense heat that can spike grow room temps or burn plants
Easy to set up and operate, even for relative beginners You’ll need additional equipment to operate them, including an electronic ballast and reflector
Produces excellent yields HID bulbs degrade over time, and you will have to replace them periodically
Reliable and consistent HID lights are very power-hungry and can significantly increase electricity bills
Options for growth and flowering

HID Light Costs and Expected Lifespan

As discussed, you can find complete HID lighting kits that include a lamp, a ballast, and a reflector for €150 and up. The low initial cost, however, will be offset by the higher operation cost (i.e. your electric bill).

The bulb lifespan is approximately one year. In turn, you should replace your bulbs annually to maintain optimal light output.

Yield per HID Light

You can expect around 0.5–1g+ per watt, which is roughly 300–600 grams/standard light.

LED GROW LIGHTS

Just a few years ago, LEDs were not suitable for “serious” grows, aside from providing light for seedlings or clones. However, LED technology has come a long way in a short time.

LED GROW LIGHTS

Just a few years ago, LEDs were not suitable for “serious” grows, aside from providing light for seedlings or clones. However, LED technology has come a long way in a short time.

Most quality LEDs emit a light that works for both veg and flowering, while some come with a switch to change the light spectrum according to the appropriate phase. Modern LED grow lights, such as those with COB (“chip on board”) technology or “Quantum boards”, can now provide solid light intensity and penetration, even for the most demanding grows. Today, LEDs can rival, or even surpass, other types of grow lighting, including HID lights. That being said, you need to get the right ones. These lights tend to be some of the most expensive, but they can also save you some serious money in the long-run.

LED PROS LED CONS
Most energy-efficient type of grow light (saves money and energy over time) High-quality fixtures with modern modules can put a decent dent in your wallet
LED lights run much cooler compared to HID lighting, barely producing any heat at all There is no industry standard for LED lights
Cuts back on cooling costs and reduces risk of burning plants Cheap models on the market produce inferior results
Most commercially available LED grow lights are “plug and grow”—no special ballast required Potentially lower yields than HID
Streamlined; can support both veg and flower
LED PROS LED CONS
Most energy-efficient type of grow light (saves money and energy over time) High-quality fixtures with modern modules can put a decent dent in your wallet
LED lights run much cooler compared to HID lighting, barely producing any heat at all There is no industry standard for LED lights
Cuts back on cooling costs and reduces risk of burning plants Cheap models on the market produce inferior results
Most commercially available LED grow lights are “plug and grow”—no special ballast required Potentially lower yields than HID
Streamlined; can support both veg and flower

LED Light Cost and Expected Lifespan

You may find a low-quality LED fixture for a single plant for €120. But for good LEDs from a reputable brand, expect to pay several hundred euro, even up to €2,000. You get what you pay for with LEDs, so it’s always worth doing your research and finding a reputable brand.

Good LED grow light fixtures have a lifespan of 5–10 years.

Yield per LED Light

0.5g–1.8g per watt, depending on the make/quality of the light.

LEC GROW LIGHTS

LEC lights, also called ceramic metal halide (CMH) or ceramic discharge metal halide (CDM) lights, are the last type we’ll be discussing today.

LEC GROW LIGHTS

LEC lights, also called ceramic metal halide (CMH) or ceramic discharge metal halide (CDM) lights, are the last type we’ll be discussing today.

The name also hints at the difference between LEC lights and conventional HID lights. LEC lights use a ceramic arc tube, rather than the quartz version found in regular MH lights. The result is a more natural colour, more lumens per watt, and a longer lifespan. LECs include built-in ballasts, so that aspect of setup is very simple.

While modern LED lighting is now becoming the de-facto standard in most grow rooms, LEC lights do have certain benefits. This makes them an interesting alternative to other types.

LEC PROS LEC CONS
Emits a natural light spectrum (easier to see your cannabis and spot issues) UV-B light is harmful to humans (safety equipment is needed to reduce risk to skin and eyes)
LEC lights give off UV-B rays that may improve yield or trichome production High setup cost
Simple setup and operation Generates lots of heat
Longer life-span than HID lights Slightly less powerful than HID lights
UV-B rays are blocked by glass
LEC PROS LEC CONS
Emits a natural light spectrum (easier to see your cannabis and spot issues) UV-B light is harmful to humans (safety equipment is needed to reduce risk to skin and eyes)
LEC lights give off UV-B rays that may improve yield or trichome production High setup cost
Simple setup and operation Generates lots of heat
Longer life-span than HID lights Slightly less powerful than HID lights
UV-B rays are blocked by glass

LEC Light Cost and Expected Lifespan

Decent LEC grow light fixtures start at €250–300, with higher-end models setting you back up to €1,000. The bulbs also cost somewhat more than normal MH/HPS bulbs.

On the plus side, LEC bulbs will last about twice as long as HID ones, approximately two years.

Yield per LEC Light

When utilising LEC lights, you can expect up to 1.5g per watt.

Which Lights Are Best for Growing Cannabis?

So, what type of grow lighting is best? This is a decision that will depend on various factors, including the size of your growing area, the type of weed you’re growing, and, last but not least, how much you can spend.

If you require a light for seedlings and clones, or you happen to have a “micro grow” in a very small space (like a cupboard), you are likely best off with a simple CFL light.

For slightly bigger grows, consider a decent LED light anywhere from 400–600W. As there won’t be much heat from the light, you may be okay with a simple exhaust system and a fan.

For medium to large growing operations, you can look into high-end LED fixtures and LEC lights, or go with proven HID lighting solutions.

Don’t Just Look at Wattage — Power Equivalents Between Types of Lights

Now, be aware that a 200W CFL isn’t the same as a 200W light LED, and neither are the same as a 200W HID. The wattage only indicates how much power the fixture uses, not saying anything about the light output. Because lighting technologies differ in their efficiency, you can’t compare them based on their wattage alone. The only type of light where one can expect certain yields (given a particular wattage) would be HID lights, as these are standardised.

Likewise, this also means that a LED fixture stated as being 600W doesn’t necessarily emit the same amount of light (and therefore produce the same yields) as, say, a 600W HID light. Honestly, the only way to determine true light output is to go over the specs from the manufacturer. Better yet, ask other growers for their experiences with a particular make or type of light—that way you’ll know what to expect.

Lights, Lights, Lights: Illuminating Your Options

Choosing the right grow light for your cannabis is among the most important decisions you’ll make.

If you want superb yields, you definitely can’t bypass getting at least a 600W or stronger HID light, or an equivalent LED or LEC. If, on the other hand, you’re looking after seedlings and clones, a less powerful CFL will do.

Most importantly, don’t spend money on a grow light without getting informed at first. A great “bargain” may ultimately just be a waste of your hard-earned cash. If prices for a good light are intimidating, you can also look into DIY solutions! You can find all sorts of kits online that come with the necessary parts. That way, you can save some money while getting a quality light that will serve you and your plants well.

In this article, we’ll be comparing grow lights made for indoor cannabis cultivation, looking at their pros and cons, and seeing what lighting solution is best.