If you’re new to cannabis and are considering indoor growing, stick around. The topic of marijuana grow lights is somewhat complex, and there’s a lot to cover.
Illuminate yourself on this complicated topic and learn how to determine the best lights for your situation. Let’s jump in and get started.
A few words about the cannabis light cycle
The light cycle is a crucial element in cultivating marijuana indoors. The three cannabis growing stages are seedling, vegetative, and flowering. The amount of light plants receive during vegging and flowering must be carefully regulated to get the best results.
In nature, cannabis grows under the sun. Over millennia, it adapted to its environment to survive. The species adopted several traits, such as the production of cold-resistant resin and photoperiod-dependent growth, amongst many others.
Long summer days provide the best opportunity for vegetative growth, so cannabis gradually adjusted to this seasonal variance. The best lights for indoor growing try to simulate these long sunlit days.
Shortening fall days tell the plants that winter’s on its way, bringing with it devastating frosts. In response, the marijuana’s survival instincts engage, kickstarting flowering in an attempt to reproduce before its life cycle ends.
Indoor gardeners raising cannabis seeds recreate these conditions by managing their illumination periods. Most run their lights for at least 18 hours a day during the vegetative stage. Flowering begins once the plants experience 12 or more hours of darkness daily.
This dark period is critical for a healthy, productive harvest. Failure to provide an uninterrupted night may result in various issues, from regressing to vegetative growth, malformed buds, or hermaphroditism.
Invest in high-quality digital timers to ensure your photoperiod runs to schedule. If you raise a non-photoperiod strain, your autoflower light schedule becomes irrelevant. These plants begin flowering after a short vegetative period, regardless of the light received.
Do I need a grow light for weed?
Growing weed inside without lights is impossible. If you plan to cultivate in a controlled environment, the simple answer is yes—you need a grow light for weed. All plants require energy in the form of photons to perform photosynthesis. Your cannabis could survive inside using ambient light from household sources and windows, but its productivity would be nil.
While it’s technically possible to use standard bulbs to cultivate cannabis, it’s not recommended. The light they produce is limited in range, spectrum, and intensity. They also produce a lot of heat, consume more electricity, and have a shorter lifespan than marijuana grow lights.
Household bulbs aren’t designed for marijuana plants. If you want any hope of harvesting a productive yield, you must provide your crops with an adequate lighting solution.
Read on for an overview of the different lights and find a solution that fits your needs.
Which types of cannabis grow lights exist?
The most suitable lights for growing weed fall into three categories. With this knowledge, you can choose the best grow lights for marijuana to suit your budget and cultivation space.
Note! Undoubtedly, there are a huge number of grow light types apart from these three. For example, CMH (Ceramic Metal Halide) also known as LECs are premium grow light solutions that are used mostly by experienced growers. These lamps are great when it comes to increasing the terpenes and smell of the final product, making rosin or producing a large number of trichomes on weed. However, in general, most growers are happy with these three types of grow lights. In the following sections, we explore and evaluate the benefits and drawbacks of each.
Compact fluorescent lights (CFL)
CFL stands for compact fluorescent lights. These are the tubular bulbs found in countless offices and stores. CFLs produce a limited light spectrum, usually found in 6500K “daytime” and 2700K “warm white” varieties. There are also CFLs designed for horticulture, known as T5s. Cannabis cultivators usually install a panel of multiple T5 grow lights for weed in the vegetative phase.
With low costs and wide availability, CFLs are a decent choice for smaller setups during the vegetative stage. Their limitations become apparent during flowering, where they can’t provide sufficient light of the right spectrum for fruitful harvests. CFLs are a fantastic option if you’re looking for a cheap indoor grow setup for vegetating cannabis. However, we recommend opting for more powerful weed lights once flowering starts.
Pros of using CFL lights for growing cannabis
Here are the advantages of using CFL lights:
- Low cost and high availability
- Easily installed and maintained
- A good choice for beginners
- Excellent for raising clones and seedlings
- Different color, temperature, and wattage combinations available
- Low power draw means you save on electricity costs
- Don’t produce much heat
Cons of using CFL lights for growing cannabis
Here are the disadvantages of using CFL lights:
- Low-intensity output makes CFL unsuitable for more than a couple of plants
- Suboptimal flowering performance and reduced yields compared to LED and HID
- Lamps burn out relatively quickly and have a short lifespan
High-intensity discharge lights (HID)
HIDs are the oldest category of cannabis grow lights. They cover two types of bulbs: metal halide (MH) and high-pressure sodium (HPS). MH lights emit a cool blue light suitable for vegging, while warmer HPS lamps give better results during flowering. Many HID housings accept both bulbs, leading growers to use a combination of MH and HPS for the best yields.
HID lamps have been around for a long time and are slowly being overtaken by more modern solutions. Their age means they’re usually cheap to purchase, and using an HID light may help offset startup costs. Conversely, less advanced technology means that while HID lights may be affordable, they’re relatively expensive to run. A lot of energy is lost as heat through the bulky ballast and the lamps, rendering them less energy efficient than other lights.
You may find HID lights cost you more than expensive options over the long term. Despite it all, HIDs are sufficient for most small to medium-sized grow ops raising indoor weed seeds.
Pros of using HID lights for growing cannabis
Here are the advantages of using HID lights:
- Cheaper initial cost than LED setups
- Relatively easy to set up and manage
- MH and HPS lamps offer adequate lighting for both vegging and flowering
- High-intensity lighting from HPS lamps leads to excellent yields
- HID lamps are a longstanding favorite with large-scale growers due to their reliability
Cons of using HID lights for growing cannabis
Here are the disadvantages of using HID lights:
- High heat emissions that could potentially damage plants if mismanaged
- Extra equipment such as reflectors are needed to make the most of HID lamps
- Their performance slowly wanes with use, meaning you must replace them after a few growing seasons
- A high power draw makes HID lamps expensive to run over a long period
Light-emitting diode lights (LED)
LEDs are the new kid on the block when it comes to growing lights. Using the latest tech, LEDs provide an energy-efficient, advanced lighting solution. Their relative newness means no real industry standards have been put in place.
The initial expense of an LED lighting setup is the highest of all cannabis grow lights. Quality systems from a reputable brand may cost more than a thousand dollars, which is a lot to ask at the outset for new farmers.
Your investment nets you with a highly efficient setup. LEDs use about 50% less power than CFLs and 80% less than HIDs. Their low power draw and heat consumption come with a high output level, making them an excellent choice if you’ve got the money.
High-quality LED grow lights also have a much longer lifespan than CFL and HID lamps. LED setups have the potential to run for ten or even 15 years, depending on their usage. Growing autoflower with LED lights is a popular choice.
Most LED systems come with an onboard chip that regulates their functioning. They often provide settings to alter the light spectrum, making them suitable for all stages of growth in a weed greenhouse.
Pros of using LED lights for growing cannabis
Here are the advantages of using LED lights:
- The most energy-efficient lighting solution, saving you considerable money in the long term
- LED grow lights for cannabis run incredibly cool, lowering the risk of plant stress and additional ventilation costs
- LED lamps are lightweight and don’t need a bulky ballast. They’re also a breeze to install—simply plug and grow
- A full-spectrum LED grow light for marijuana plants eliminates the need for bulb changes and streamlines the process for the farmer
Cons of using LED lights for growing cannabis
Here are the disadvantages of using LED lights:
- Advanced circuitry and tech make LED lights the most expensive option
- A lack of industry standards makes it hard for customers to make informed decisions
- Some retailers produce poorly made and falsely marketed LED systems with subpar results
- Yields may not quite match those of plants grown under HID lights
What is the light spectrum, and how does it affect cannabis growth?
The light we see makes up a tiny section of the much larger electromagnetic (EM) spectrum. EM radiation visible to the human eye is what we refer to as light. It can be further broken down into its constituent colors. Passing a beam of light through a prism demonstrates this property clearly, and is also seen in rainbows. Different frequencies of light travel faster or slower through a medium depending on their wavelength.
Light from the sun travels in a straight line through the vacuum of space to reach us. It must then penetrate through the atmosphere before reaching the surface. The angle at which it passes significantly affects the light waves. When the sun sits high in the sky during summer, its rays hit the atmosphere straight. As a result of its angle of attack, less light is diffused and scattered during transit. A light for growing weed attempts to replicate these wavelengths.
Later in the year, when the sun is much lower in the sky, its angle of approach is more oblique. The light must travel through more atmosphere and experience higher levels of scattering.
Light frequencies in the blue range of the EM spectrum have shorter wavelengths. As a result, they’re more susceptible to the scattering effect of the atmosphere. The light that reaches us during fall and winter carries more energy from the red part of the spectrum.
How does this affect cannabis growth? The answer is a phenomenon known as photomorphogenesis. This process occurs when light conditions drive changes in the development of a plant, in this case, cannabis.
Photoperiodism is a photomorphogenic mechanism through which unaltered marijuana plants flower. Phytochrome cells detect shifts in the light spectrum, alerting the plants to the oncoming winter. Once they sense red light for a specific period, flowering begins.
If you’re outdoors, this happens naturally. Indoor cultivators must replicate these conditions by choosing the best weed growing lights for each stage. This decision is usually achieved through a combination of lamps, full-spectrum LED setups, or dual spectrum bulbs.
Dual spectrum bulbs
Don’t like the sound of switching out bulbs mid-grow? A full-spectrum LED lighting setup out of your budget range? Dual spectrum bulbs might be just what you’re looking for. A dual spectrum bulb produces both blue and red light. It provides the necessary amount of blue light during vegging and the all-important red light once flowering begins.
This kind of light is classed as an HID. The drawbacks and benefits of dual spectrum bulbs are the same as limited-spectrum MH or HPS lamps. While they’re relatively inexpensive, they run hot and consume a lot of power.
However, a dual spectrum bulb saves you money on buying additional ones and gives vastly better results than a single spectrum lamp.
Other things to consider when choosing the best grow light for cannabis
A lot to take in, right? It’s understandable to feel a little overwhelmed by the different choices and terminology. The best advice is to take your time and make a shortlist of options. Here are some more factors to consider that hopefully will make the selection process easier:
Light intensity
When discussing plants and marijuana grow lights, we use different terminology. Typically, light energy is measured in lumens. The amount of light reaching a surface is measured in lumens per square meter or lux.
These terms relate to light energy visible to the human eye. Scientists use photosynthetically active radiation (PAR) instead of lumens when dealing with plants. The amount of light interacting with a plant is known as photosynthetic photon flux density (PPFD).
PPFD is measured in micromoles per second per square meter. Cannabis is a high light intensity tolerant plant. It can utilize large amounts of PAR energy to boost its growth and productivity.
Remember that plants need extra carbon dioxide to take advantage of light intensities greater than 900 PPFD. Higher light intensity increases transpiration rates, meaning crops go through more water.
If you want to push your plants to reach their potential, an awareness of PPFD goes a long way. What makes things trickier is that PPFD varies over distance, so it must be calculated based on the lights’ PAR values.
Thankfully, plenty of online PPFD calculators are available to help you optimize your setup.
Heat emission
Every light for growing weed produces heat energy during use, but some emit far more than others. HID lamps run particularly hot, as do their bulky ballast units. If you want to prevent cannabis heat stress, this is something you must account for.
If you run an HID grow-op, you may need to install extra ventilation and fans to keep the temperature down. Additionally, the heat emitted by HID lamps means they must be installed further away from the canopy than LED or CFL lights.
Energy consumption
Energy consumption and costs are a significant concern for those growing weed indoors. The numbers quickly increase if you forget to factor in the price of running weed lights for 18 hours a day.
The more you shell out initially, the more money you ultimately save in the long run. The simple fact is that energy-efficient technology is advanced, costly to produce, and thus expensive to buy.
In terms of energy efficiency, the least popular are HID lamps—by a significant margin. These old, power-hungry lights are cheap to buy but not run.
CFLs fall somewhere in the middle. Much better than HIDs, they’re still not as efficient or long-lasting as LEDs. On the positive side, they’re also not as expensive.
LEDs take the prize for energy efficiency. Their power draw is considerably lower than CFLs and dwarfed by the electricity-guzzling HID varieties. Their relative newness and complex internals make them expensive and often out of the price range of hobbyists.
The cost of grow lights for weed
The price points for cannabis growing lights vary, but as a general rule, HIDs are the cheapest, followed by CFLs, then LEDs. Here’s a quick rundown of the average prices of some popular models from each category:
1. HID grow lamps
- Sun System HPS 150 Grow Light: around $90.00
- iPower Horticulture 400 Watt Grow Light System: circa $120.00
- Gavita Pro E-Series 6/750e DE Flex: just over $400.00
2. CFL grow lamps
- VIVOSUN T5 Grow Lights 4 ft, 432W(8 X 54W): slightly more than $150.00
- Hydrofarm Agrobrite FLT48 T5 Fluorescent, 4 Foot, 8 Tube System: around $250.00
3. LED grow lamps
- Covert LED-X 250 Watt Full-Spectrum LED Grow Light: close to $300.00
- Growers Choice ROI-E420 LED Grow Light: just over $500.00
- Gavita Pro 1700e LED 645 Watt Grow Light: less than $1300.00
- PhytoMAX-3 8SP Grow Lights: also slightly under $1300.00
Don’t let the purchase price of your grow lights entirely dictate your decision. Remember that expensive lamps are more energy-efficient. A higher initial investment could result in long-term savings thanks to lower power consumption.
The shape of the lights
The shape of your light setup affects its intensity and coverage. A reflector hood is necessary to redirect the light from HID lamps.
The material and shape of these reflectors determine how well they disperse light. The best material is a shiny metal like aluminum. An uneven, dimpled surface provides better light dispersion than a smooth one.
The shape of a reflector is also important when maximizing light efficiency. Despite covering an impressive area, larger ones are not always better. Light from the bulbs must travel further, leading to more falloff, especially toward the outside of the reflector’s footprint.
Smaller, curved reflectors may not cover bigger areas but direct higher intensity light to your plants. Reflectors also impact heat emission. Closed, box-style ones tend to capture a lot of energy reflected down towards the canopy. Simple, open-ended hoods allow more heat to escape upwards and may be placed closer to the plants.
Cooled varieties provide the reflective capacities of closed ones while avoiding the added heat. They add to your grow-op’s power draw and running costs.
LED lights for cannabis flowering generally don’t use reflector hoods. Instead, the bulbs feature an integrated optical lens that controls light spread. These allow the user to adjust the intensity via the lens system easily.
PAR values
As mentioned previously, PAR stands for photosynthetically active radiation and refers to the section of light radiation used by plants to grow. Generally speaking, the higher the PAR value, the higher your yields.
Measuring PAR values requires expensive equipment that most growers can’t access. Most reputable sellers provide a PAR chart to consult when shopping for indoor growing lights.
Check this chart and ensure the lights provide high light intensity levels across its footprint. While some light falloff is inevitable, the best grow lights for cannabis deliver relatively uniform PAR values.
Reflective materials
Lining your grow room with reflective materials can significantly increase your productivity over a non-reflective setup. Most tents on the market take care of this for you, but it’s easy to do yourself.
A common option is to paint the walls of your cultivation space plain white. This idea is reasonably effective but takes more effort than it’s worth. A better choice is to line your room with reflective mylar sheeting.
This material is widely available, highly affordable, and produces excellent results for its cost. It’s also easy to install and uninstall, leaving your walls mostly unharmed.
Light up your life with indoor cannabis
Now that the topic of the best lights for indoor growing has been illuminated, get out there and start your adventure.
If you have an indoor grow setup, you need lights. Whether you choose CFL, HID, or LEDs is entirely up to you based on your space, your strains, and of course, your budget.
If your head is spinning after all that information, you could always go in another direction. Our outdoor winter strains are an excellent alternative to cultivating indoors in cooler climates. Whatever you decide, remember to stay safe, have fun, and enjoy yourself. Don’t forget to shop our wide selection of premium marijuana seeds with unbeatable genetics.
