Grow Light Guide
Are you just starting to grow and wondering what lighting you need for your grow room? Don't worry, we've got a break down of lighting options as well as some recommendations. Are there more lighting types than what we list? Yes, but we're keeping things simple and listing the most common grow light options.
Fluorescent Grow Lights
T5 and CFLFluorescent lighting is one of the simplest ways to light your garden and is most often used in a grower's veg room. Another reason for their popularity is that they produce less heat than HID since they are more efficient. The most common fluorescent grow lights are T5 grow lights and CFL grow lights. T5 Fluorescent grow light fixtures for indoor gardening are all-in-one systems, meaning that no external ballast in needed and has built in reflectors, and in most cases will come with bulbs installed and may offer a grow or bloom version. CFL grow lights for indoor gardening are usually either smaller 25w medium base socket (standard light socket) or 125w CFLs. Be sure you are buying industry specific lighting, like the lighting we sell, rather than buying from a lighting supply store. Indoor gardening industry CFLs are self-ballasted, meaning they just screw into a CFL reflector and you're good to go. Buying a cheap 125w CFL from a general lighting supply store and you'll most likely end up with a non-ballasted bulb as it is meant to go into an outdoor lighting fixture that has a built-in ballast.
The trade-off for the simplicity and lack of heat comes in the form of less usable plant growth specific light and less light penetration. Many growers use fluorescent for veg growth only or as supplemental lighting in flower, as it can produce lackluster results as the primary light source in bloom due to the lack of light penetration. If you do flower with fluorescents, we recommend using a canopy growing method like a screen of green. This allows you to maximize the fluorescent lighting and reduces your need for penetrating light. For grower's looking to maximize the T5 veg lights, Hortilux recently released the first and only indoor gardening veg specific T5 bulb called the PowerVEG Tube, though they are about 3x the price of a standard T5 grow bulb.
HID Grow Lights
Metal Halide (MH) or High Pressure Sodium (HPS) Lamps*
Both MH and HPS fall under the High Intensity Discharge (HID) category of grow lights. HID grow lights require a reflector/fixture, bulb and ballast. These pieces are all separate unless kitted together, and occassionally you may see a fixture with integrated ballast.
MH lamps produce a blueish to yellow spectrum that is especially suited to the vegetative/growing stage of plant growth. HPS lamps produce a red/orange spectrum that is especially suited for the blooming/budding stage of plant growth. So if you're vegging your plants Metal Halide is the better option, and if your blooming your plants High Pressure Sodium is the better option. If you can only have one bulb, typically you will want to pick a HPS lamp since the blooming yield is the more important aspect. Both MH and HPS bulbs produce a significantly higher amount of heat (and are, therefore, less energy efficient) than LED or fluorescent fixtures, but generates better usable light than fluorescent and is more affordable than LED grow lights.
Dual Arc Lamps
Dual arc lamps are another bulb type for HID lighting. While a dual arc lamp is technically a HPS lamp, dual arc lamps contain both bulb type components to give you a more natural, fuller spectrum. For example, a 1000W dual arc lamp is contains a 600W HPS component and 400W MH component.
Double Ended Lamps (DE)
Double Ended Lamps have gained popularity in the past couple of years. Voltage is generated at both ends for more even burning of gases inside the tube and a more stable spectral output, allowing them to have a 10% increase in light intensity and PAR output over traditional HPS lamps. DE lamps also emit more UV and IR light (over traditional HPS), increasing potency and essential oil production in plants. Because these bulbs degrade slower than traditional HPS lamps, a double-ended lamp will still be putting out 90% of its original intensity after 10,000 hours. While DE grow lights still need 3 traditional components like standard HID lighting, ballast, lamp and reflector, DE lighting is more commonly available in all-in-one reflector/ballast units than regular MH/HPS grow light setups.
The trade-off for Double Ended grow lights is that you can't use traditional HID hardware. DE grow lights require specific DE reflectors, DE exclusive or compatible ballasts, and specialty DE grow light bulbs. Besides different equipment, you'll also need to plan your grow room setup for open reflectors, as most DE reflectors are open with no cool ports or glass. This is due to the glass filtering out a large portion of the UV and IR that the DE grow light puts out, making an air cooled DE grow light not much better than a standard HPS grow light.
Ceramic Metal Halide (CMH)
Ceramic Metal Halide grow lights (sometimes referred to as LEC or CDM) are the latest popular tech to light gardens. CMH have a very broad light spectrum and emits UV, giving more similar of lighting to natural sunlight compared to traditional HID lamps. CMH grow lights are often used as primary veg lights, primary lighting for SOG applications, or as supplemental full spectrum in larger grows. CMH grow lights are 10-20% more efficient than a traditional metal halide and have increased PAR to Watt when compared to traditional HID grow lights. CMH lamps tend to have a longer life than traditional MH, up to 24,000 hours (with 87% of its original intensity at 20,000 hours) vs. traditional 16,000-20,000 hours (with 50% intensity lost after 10,000 hours). While it's a non-factor for plant growth, some people think it's important to include the CRI (Color Rendering Index) rating for lamps. CMH lamps are generally in the 80-96 CRI range (where the sun produces 100 CRI).
Like DE grow lights, Ceramic Metal Halide grow lights use open reflectors and are often all-in-one type units. CMH grow light setups consist of a specialty bulb, reflector and ballast. Also like DE grow lights, CMH grow lamps have a special socket and require a special CMH reflector and ballast. While some growers are reporting success flowering with CMH grow lights, we don't recommend CMH in place of 1000w or 600w HPS grow lights.
LED Grow Lights
LED Grow Lights are one of the most efficient lighting options on the market, and arguably one of the best with the latest generation of high-end LED grow lights. We say high-end because some of the cheap LED grow lights use older tech, weaker/lower wattage LED diodes, among other issues, and typically aren't good for much besides some veg growth. Though if you are just growing crops like greens or lettuces, herbs and lower light plants you'll probably do fine. For flowering you'll want good LED lights with higher wattage diodes and multiple spectrums like KIND LED.
Grow Light Comparison
HID vs LED vs Fluorescent
Generally speaking, HID is currently the most popular type of grow lighting. However, due to their greater energy efficiency and growing technology, fluorescent and LED fixtures are quickly gaining ground. HID light setups are usually cheaper up front, but create a lot of heat and use a lot of electricity causing additional electric costs as well as equipment costs like A/C. To help give a comparison we're going to break it down by growth stages.
Seedlings and clones don't need much light, and the light they need can't be too intense. The most common propagation lighting that we see used, and that we recommend, are fluorescent grow lights. This is because fluorescent grow lights produce enough light to grow the young plants but isn't too harsh to burn their little leaves or create too much heat. After fluorescent grow lights, LED has become the second most popular method that we see. We're talking your more basic LED grow lights like the ones that screw into a typical household light socket, strip lights, and ufos, not your K5 series KIND LED grow light. The least recommended grow light for propagating seedlings or clones would be HID (Metal Halide) due to the heat, intensity, and just overall overkill. If you've got a 150w metal halide 3 feet about your seedlings you'll probably do fine, everything else is overkill and will probably hurt your plant more than help unless you've got the lamp all the way to the ceiling. For overall performance to the cost/efficiency we'd recommend fluorescent grow lights, with 125w CFL and a basic reflector and light hangers typically coming in a little cheaper than a 2 tube 2 foot T5 fixture and giving you more light. If you're able to find some cheap veg LED bulbs on sale cheap you can build out a great little propagation setup as well.
The veg phase of plant growth is when you bring in the more intense light. Fluorescents are still commonly used, though with larger fixtures and more bulbs. Hortilux's recent innovation in the past couple of years with their specialty T5 bulb has definitely improved the typical T5 veg, though they come at 3x the price per bulb. LEDs are great for veg too, even better if the LED is specifically for veg like KINDs new Veg L600. Even the bad LEDs do a decent job vegging plants. Many growers have tossed their cheap LEDs that failed to produce in flowering into their veg room with good results. HID Metal Halide grow lights are the gold standard for vegging plants for the past few decades. They produce good results and can veg some larger plants that less intense lights like fluorescent may have trouble doing. These days you have more specialty bulbs like Hortilux's Blue Metal Halide (not currently recommended by our company due to many issues with their lamp compatibility and overall build quality) or Sunmaster's Full Nova. These grow lights offer about as close as you can get to the sun as possible. Ceramic Metal Halide is now becoming popular and is praised for it's veg growth as well.
We can't call a clear winner for veg as all lighting types perform well and have their place. Fluorescents are cheap/easy/efficient for veg, with the option to spend a little more and buy specialty T5 tubes from Hortilux for even better results. LED grow lights work great, even the cheap ones, giving you a long-lasting light that doesn't degrade but at a higher up front cost. Veg specific grow lights like the KIND Veg L600 can give spectacular veg results, but with a high upfront cost. The tried and true HID grow light is always a good way to go. Even with a cheap bulb you'll get a great veg, with much more impressive results given from a specialty full spectrum daylight bulb like Sunmaster's Full Nova. Ceramic Metal Halide is another great option as well.
The bloom phase results are what everyone is after, this is where all of your hard work pays off. For blooming we typically do not recommend fluorescent grow lights. Can you bloom under T5s? Yes. Can you get good results? Sometimes. For best results with T5s you need to just grow at the canopy level, trimming off everything below. T5s just don't have penetration to grow the lower portions of the plants to their full potential, wasting energy that could have been focused at the canopy. If you do that you'll get some good results, otherwise your results may be a little airy rather than dense.
Some good quality LED grow lights can work magic in bloom. Due to the wide array of spectrums we've seen some very dense, frosty and sticky results from LED that some other lighting types just can't do. Some growers may argue that HPS is the best and they pull more weight off that than LED. Yes, maybe, but how about the quality? Does it look like you just sprayed it with a can of that spray-on Christmas tree snow? The cost of LED grow lights is much higher initially than other light options but you pay less for energy, cooling, fans, bulbs, etc.
HID lighting, specifically High Pressure Sodium grow lights, is the go-to bloom lighting for most grow rooms. Great results and lower startup costs make it ideal for most growers. High-end bulbs produce even better better and the use of specialty bulbs, like finishing spectrum bulbs, can boost results and add more of the frosty quality that wide/multi-spectrum lights like LEDs offer. Some growers are also using Ceramic Metal Halide for their bloom grows, though they perform better as veg lights than bloom.
There is no clear winner in our recommendation as there are many trade-offs and differences, with some being the preference of the grower and their style. T5s are our least favorite recommendation, though if used properly with a canopy scrog can provide good results. Due to the ease and affordability T5s can be a good option, just be sure to grow it right. High quality LED grow lights like KIND are one of our favorite bloom recommendations. Though the high initial cost can be a turn-off for lots of growers, especially new growers. Spending over $1,000 initially on a grow light can be difficult unless you have the extra cash lying around and are sure you are going to stick with the hobby or business. We recommend traditional HPS lighting for most growers, especially newer growers looking for good results at an affordable price. HID lighting is affordable and even low-end bulbs can produce great results. The trade-off is that you have to replace bulbs at least yearly, due to the inefficiency the lights draw high wattage and generate more heat than other lighting types.
Grow Light Wattage Footprints [Air Cooled (AC) and Open]:
Below are some common recommendations for lighting based on the grow room footprint. The recommendations are based on the square footage with recommendations for Air Cooled (AC) grow lights and open reflector grow lights. Recommendations are based on a home ceiling of about 7' or grow tent height. Extended height grow tents or high ceiling grow rooms may be able to use higher wattages than the provided recommendations if desired. You may see growers using higher wattage grow lights for certain sizes than the below recommended wattages. Using higher watt grow lights may require additional cooling for the space due to the extra heat and is not recommended for a new grower.
Grow Room Footprint
2'x2' -- 250W AC or 150W Open
2'x'4' -- 400W AC or 250W Open
3'x3' -- 400W AC or 250W Open
3'x5' -- 600W AC or 400W Open
4'x4' -- 600W AC or 400W Open
5'x5' -- 1000W AC or 600W Open
4'x8' -- 2x600W AC or 2x400W Open
8'x8' -- 4x600W AC or 4x400W Open
5'x10' -- 2x1000W AC or 2x600W Open
10'x10' -- 4x1000W AC or 4x600W Open
8'x16' -- 8x600W AC or 8x400W Open
10'x20' -- 8x1000W AC or 8x600W Open
*A Note About the Term Lamp: The lighting industry refers to certain light bulbs as lamps. This is because bulbs like metal halide, high pressure sodium, and fluorescents are technically lamps due to the fact that they uses gases to burn rather than a filament, making them a lamp and not a bulb by definition. Most people call them bulbs either way. While you might run across some people who insist on using this term, most grow store employees will have no problem knowing what you mean if you say "bulb." Just make sure you clarify "grow bulb" if you're in a more generalized store.