what lights work for growing weed

Another reason why you might need lights for growing weed is when you grow multiple plants. A single plant in a sunny room or discreetly placed on a balcony can grow just fine with sunlight and perhaps a small LED, such as what we sell on A Pot for Pot’s website. However, multiple plants will need more substantial lighting.

Wattage also helps determine how far away you should keep your plants. Generally speaking, higher wattage lights need to be positioned further away from your plants because they can burn them. LED lights are an exception to this rule because they give off surprisingly less heat when compared to the other types of lighting with the same wattage.

The Lithonia Light GRW is a hanging light that is suitable for both larger indoor weed grow operations as well as small hobby gardens. This is because you can simply adjust the chains to adapt the light system to the evolving size of your plants.

Top 10 Indica Strains.

Kelvins refer to the warmth and color of the light being emitted. During the vegetative stage, cannabis thrives best when provided cool daytime blue light with approximately 6,400 kelvins. Conversely, flowering cannabis performs best with a warmer red light of 2,700 kelvins.

Whether you are new to growing marijuana indoors, or a certified expert, you will certainly agree that the Roleadro LED panel is an excellent option because of its versatility. Depending on the configuration of your indoor grow space, the Roleadro LED panel can be used on its own or in combination with other lights. This light emits both blue spectrum light and red spectrum light, meaning your photoperiod plants will have all the light they need.

The G8LED Mega LED Grow Light is perfect for indoor plants since it provides the full spectrum that they need, combined with massive coverage. It covers 18 square feet! For photoperiod plants, you can boost its performance during flowering by installing a few 90W red flower boosters. The buds that form will be huge and dense with cannabinoids.

The Sun System light emitting ceramic provides all the far frequencies of red light in addition to all the blue light, so your plants will have all the light needed to thrive and produce huge buds. This full spectrum is superior to what is provided by other lights currently on the market. The Sun System is also easy to set up and was designed to reduce the radiant heat generated by its arc tube.

What type of light is best for growing plants indoors?

Like plants growing outdoors in the sunlight, indoor plants grow best under full-spectrum bulbs.

Light Spectrum.

Lumens is a measure of how much light a given light source emits during each second the light is on. Like the light spectrum, lumens are more relevant for photoperiod plants. “Regular” cannabis plants require varying amounts of lumens during the different stages of growth. For example, they need between 2,500 and 5,000 lumens per square foot in the vegetative phase, but it jumps to 10,000 lumens per square foot during the flowering phase.

As an LED, the 440Watt California Lightworks Solarstorm will work for your plants’ entire lifecycle. The light provides five bands of high PAR (Photosynthetic Active Radiation) from the deepest blue colors to the deepest red colors of light – a rich blend of everything your marijuana plants need.

Can I leave my grow light on 24 hours?

This fluorescent light is very similar to the fluorescent lights you find in people’s homes. However, the Vivavolt T5 also provides the wide spectrum that photoperiod marijuana needs to grow indoors.

3. Advanced Platinum Series Grow Light.

Grow with the Sun.

Harvest up to a pound.

This 12-band LED light is ideal for a variety of indoor plants, including weed. One of the best things about this light is the money you can save. When you replace other lights for growing weed with the Advanced Platinum Series LED light, you will immediately notice a drop in your energy use.

Our complete grow kits include everything you need to go from seed to your very own supply of high grade medical cannabis.

Whether you are growing a single plant, or a massive garden, LED lights are some of the best options around.

Consider how often you’ll be growing weed and how long it will take to pay off the initial investment—if you grow once a year, it’ll take a lot longer to pay off an expensive light than if you grow multiple harvests a year.

You can find lights for under $100, but they may be low quality and not produce the right spectrum of light, and you can also easily spend as much as $2,000 for a large, state-of-the-art LED.

There are many different kinds of lights out there, so it can be daunting to know where to begin. Here’s a guide to four basic types of grow lights on the market and the pros and cons of each.

How many grow lights do I need to grow weed?

There are daylight bulbs and warm white bulbs; the former better for vegetative growth, and the latter for flowering.

Another consideration with cost is that some lights run hotter than others—HIDs, for example—so they may require additional fans or an AC unit to cool down a grow space. Extra equipment means more electricity, also driving up your utility bill.

The downside to CFLs is they aren’t great for flowering plants, and growers will usually use another type of light to finish plants. CFLs just don’t generate enough intense light for plants to pack on weight.

Some grow lights are more expensive than others, but also more efficient, saving money in the long run. Some lights are bulky with many parts, some light in weight, and some are better suited for young or mature plants.

HID (high-intensity discharge) is an umbrella term under which MH and HPS bulbs fall, which we’ll discuss more below. These types of lamps have a hood that reflects light and bulbs that are enclosed capsules containing a gas, as opposed to bulbs you’d find in your house, which have a filament that heats up.

CFLs (compact fluorescent lamps) are fluorescent lights similar to what you’d find in a school or office building, but smaller. For growing weed, they are usually called “T5s”—the “T” stands for “tubular” and the “5” refers to its diameter, “⅝”.

Other considerations when choosing a cannabis grow light.

Both types of HIDs are usually inexpensive to buy but will eat up electricity. HIDs throw off a lot of light and heat, which the plants need to bulk up and get potent. But, they run hot, contain heavy metals, and ballasts can fail.

These bulbs contain mercury and metal halides, produce a blueish light, and are commonly used for vegetative growth. They require a ballast to regulate the current. In the past, ballasts have been big and bulky, but digital ones are now available.

Aside from the price of the actual light, also take into account utilities—all lights will add to your electricity bill every month, but some more than others. High-intensity discharge lights—known as “HIDs”—may be cheaper to buy but can gobble up electricity, whereas LEDs are more efficient and kinder on your electricity bill but usually more expensive to buy.

As with HIDs, you can find CFLs at any local grow shop.

How much does a grow light cost?

Here are a few different HID grow lights at different price points.

Make sure you have enough outlets and power available in your breaker board for your grow space to comfortably accommodate all equipment. Figure out all pieces of equipment, such as lights, fans, possibly an AC or dehumidifier, and calculate how much power they’ll require. You’ll be running this equipment every day for months, so if you don’t have enough power it can be dangerous. Never overload an electrical outlet.

However, because of their low price, if you’re new to indoor growing and not sure how often you’ll do it, you may want to invest in an inexpensive HID light at first to test the water.

You can find HID reflector hoods, as well as MH and HPS bulbs at any local grow shop.

Grow lights allow you to control exactly how much light your plants receive, ensuring they get the same amount of light day after day, without the grower having to solve problems with bad weather or cloudy days that happen in an outdoor environment.

“What lighting source should I use for my licensed cannabis grow?”; “I am comparing LED to HPS for my cannabis operation. Which source do you recommend?” These are questions people ask me almost on a daily basis. We have covered this question in past posts on our blog, like this one by our very own head of marketing: LEDs vs Traditional Lighting but most cannabis growers know that this crop is different than most and many growers have experimented with lighting technologies on a small scale to find they can sometimes increase terpenes and THC levels just by changing their light sources. To begin, let’s unpack the information that exists on this complex topic.

To use the PL Light TopLED R/MB as an example: 320W fixture with PPF of 860 μmol is 2.7 μmol/J (860 / 320 = 2.6875) where the 1000W DE HPS has an output of 2100 μmol is 2.1 μmol/J (2100 / 1000 = 2.1). This is important because I have sat in many presentations, by LED manufacturers, who show how quickly they can hit a good ROI with their LED and use 1.85 μmol/j as their HPS comparison. They’re not lying about this but they are using the old single-ended screw in 1000w HPS lamp in the comparison. These lamps have an output of 1850 μmols at 1000w. But, it is an old technology only in use by small hobby grows these days. I have seen manufacturers use as low as 1.7 μmol/J for HPS which would be the equivalent to the end of life of the old HPS technology.

When comparing both technologies, always compare light levels of the entire grow and not just fixture to fixture. I cannot stress enough that there is no such thing as a 1-for-1 replacement of HPS by LED! That simply does not exist in the marketplace. Yes, there are LED fixtures that exist when measured directly beneath the fixture. The output looks equal to or even greater than an HPS. But, when you move the PAR sensor any direction from centered beneath the LED the light level decreases much more under the LED than any HPS fixture!

Unpacking Existing Information.

With all of these factors above, how do we answer our initial questions?? Quite frankly, there is no simple answer! Every grow is different – from different: strains being grown, growing climates by geography, style of growers, indoor versus greenhouse, etc. All of these factors will weigh heavy on what is better for you!

The best advice I have is to get a comparison of your ROI done by a versatile company. One that can offer both technologies where you can have light plans designed to the same levels with both technologies. Don’t trust just what the LED guy says or the only HPS guy says. Look at both, do your own math. Know what works for the strains you are growing and measure your own ROI. The easiest way to do this is going to this link and ask your local PL Light Territory Manager for advice as we are the “Lighting Knowledge Company” and whether you decide to use LED or HPS, you will get a true and honest comparison of both technologies.

One of the reasons you still hear people claiming that LED is not ready for commercial cannabis grows is because the reflectors from an HPS fixture mounted 4 ft from the canopy will provide a wide angle of light so the crop will receive light from the fixture directly above as well as the lights from the next row over and even 2-3 rows away. This light is coming in from different angles hitting the crop beneath the canopy leaves that are causing shadows from the light above. This does not happen if you are using an LED fixture that is a big panel of LEDs or made up of multiple LED bars where they have to be mounted 9-12 inches from the canopy. You get no crossover from the fixtures but only shadowing from the top of the canopy.

Do this math with your LEDs as well. The PL Light TopLED is 320 watts so the BTUs will be 1092 BTUs. While that looks like a big savings it will take at least two times the amount of our LEDs to get to the same light level as a 1000w HPS. On the other side of this argument is that the LED fixtures do not provide the radiant heat as HPS and your crop roots will perform better with warmth. It is proven that there is a direct correlation between heat and crop production. Plants grow slower, producing less fruit the colder they are. In northern climates many growers rely on the heat from HPS to warm their crops.

It was only after companies like P.L. Light and Philips* introduced LED fixtures specifically engineered for truss mounting in a greenhouse, that growers really adopted this technology. These products enabled even the indoor grower to maintain some distance between the LED fixtures and the plant canopy, and resulted in production similar to growing under HPS. (*In the United States, Philips has taken the stance that they will not support sales into the cannabis industry as it is not recognized to be legal by the federal government)

LED technology has only been available on a commercial level in the horticultural industry for around three years. So realistically, they would only have had time to trial a limited number of spectrums that may yield good results for one or two strains/cultivars. We simply have not had the technology long enough to perform the testing needed!

Efficiencies.

There is a lot of information out there on the internet from various growers and lighting suppliers. You can find a contradiction to almost every point you find! Most growers agree that for young plants through the veg stage of growth you will want to have a light source with a good amount of blue light or even white (full spectrum) lighting. The main reason for this is to reduce internode stretching to produce a stockier, healthier plant.

With LEDs most will use μmol/J (“Micromoles per joule” with joule being a measurement of watts). This is easy math you can do yourself.

This is a big consideration to consider when comparing these technologies. There is no easy math to calculate an ROI for this but when comparing light plans from one source of light to another be sure to take into consideration the distance of the light source from the canopy.

After veg and moving to flower, most growers also agree that switching to a light source with more of the red spectrum is better for flowering. The old standard has been to use either CMH or fluorescents in veg and switch to HPS into flower. This is the tried and true lighting recipe for indoor cannabis growers. By far the majority of cannabis produced in North America today is grown in this way. With the onslaught of LED lighting manufacturers jumping into this new “green rush” of opportunities we are seeing this standard lighting recipe being challenged more and more.

Light Planning.

In countries like Canada, where the federal government has legalized recreational cannabis, there is the ability to do more research. The University of Guelph is one organization that is leading the way in this research. As he states in this article from HortiDaily — Michael Dixon, Director of Environmental Control Research at Guelph says: “We have found that the optimal LED spectral recipe changes with every strain of cannabis.” This is a very important statement for growers to consider! Will you be growing just one strain in your grow the entire time? If not, what spectrum do you choose? Yet if the added blue light in flower only increases your THC levels by 4% is there a justifiable ROI in the cost of the added light spectrum?? If so, can you do that by just adding a few MH lamps? Or does the ROI make sense to go all LED? (1000w DE MH lamps are now available with the PL Light NXT 1000w DE fixtures).

Another area you should always do your own math on is the BTU calculation for your grow room. Yes, LEDs produce less heat than HPS and this can be the deciding factor. As the cost to cool your grow room can be one of your highest production costs. Your AC load is based on the amount of BTUs produced from your fixtures. This is simple math as 1 watt equals 3.412 BTUs. No matter what 1000w HPS fixture you use the BTUs from that fixture will be 3412!

There is a big misconception in the industry stemming from the LED suppliers that the ability to have your LED lights so much closer to your crop will help increase production lower into the crop. This could not be further from the truth! When your light source is closer to the top of the canopy than the shadows created from the top layer of leaves are much bigger than if the light was further away. (Use a flashlight and make a shadow on a wall with your hand. Watch how the shadow grows as you get the light closer to your hand). Also, light penetration into the crop comes from the crossover between fixtures.

ALWAYS ask for a light plan that shows an average light level in micromoles AND a uniformity average (hopefully above 90% uniformity). Most LEDs are a very directional source of lighting. If a crop is grown under lighting that is not uniform across your canopy but instead has “hot spots” and “dark spots” it will cause you trouble as the hot spots will use more water, evaporate water, absorb nutrients, etc. at a different rate of speed then the dark spots! To truly have an “apples to apples” comparison be sure to compare light plans with the same targeted light level in micromoles and close to the same average uniformity number. If a supplier cannot provide you with these numbers then it may not be someone you should be considering.

As a plant that does not have sufficient lighting in veg will not produce as well in flower. That said, the spectrum with the most blue did produce the flower with the most terpenes and THC.