Lighting Grow Light Guide - Comparison HID, CFL, Incadescent, MH, HPS

[JM]

Preface: The LED info provided here is outdated.... however, the rest of this guide is a great comparison of all different types of lighting and efficiencies involved.


Horticultural lighting systems allow you to extend the growing season by providing your plants with an indoor equivalent to sunlight. This is a great advantage for those of you who appreciate having a year-round supply of fresh flowers, veggies and herbs. Artificial lighting is also a great way to jump-start spring by starting your seedlings months ahead of the last frost. There are three main types of horticultural lighting systems.​

[SIZE=+1] HID (High Intensity Discharge) Plant Grow Lights [/SIZE]​

HID lighting is the most efficient way to convert electricity into light that is available to the consumer. There are two types of HID grow lights used for horticultural lighting:
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Metal Halide - MH
Metal halide bulbs produce an abundance of light in the blue spectrum. This color of light promotes plant growth and is excellent for green leafy growth and keeping plants compact. It is the best type of light to be used as a primary light source (if no or little natural sunlight is available). The average lifespan is about 10,000 cumulative hours. The bulb will light up beyond this time but due to the gradual decline of light, it is not worth your while to wait for the bulb to finally burn out. If you compare their lumen (brightness) per unit of energy consumed, metal halides produce up to 125 lumens per watt compared to 39 lumens per watt with standard fluorescent lights and 18 lumens per watt for standard incandescent bulbs. View MH & HPS grow lights​

High Pressure Sodium - HPS

High pressure sodium bulbs emit an orange-red glow. This band of light triggers hormones in plants to increase flowering/budding in plants. They are the best grow lights available for secondary or supplemental lighting (used in conjunction with natural sunlight). This is ideal for greenhouse growing applications.

Not only is this a great flowering light, it has two features that make it a more economical choice. Their average lifespan is twice that of metal halides, but after 18,000 hours of use, they will start to draw more electricity than their rated watts while gradually producing less light. HPS bulbs are very efficient. They produce up to 140 lumens per watt. Their disadvantage is they are deficient in the blue spectrum. If a gardener were to start a young plant under a HPS bulb, she/he would see impressive vertical growth. In fact, probably too impressive. Most plants would grow up thin and lanky and in no time you will have to prune your plant back before it grows into the light fixture. The exception to this is using HPS grow lights in a greenhouse or in conjunction another light source that emits light in the blue spectrum. Light sources that have a high output in the blue spectrum like sunlight and MH grow lights offset any stretching caused by HPS bulbs.

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[SIZE=+2][SIZE=+1]Fluorescent Plant Grow Lights [/SIZE][/SIZE]​

Until recently, fluorescent grow lights have had a low output and have been too big and bulky to be of much use as a grow light for anything more than starting seedlings. CFL and T5 full spectrum fluorescent lights have changed that. At 75 to 90 lumens per watt, these lights are energy efficient and extremely effective especially when used in numbers. Fluorescent grow lights also have better color rendering properties (more of the light emitted is used by the plant) and produce much less heat than incandescent and HID grow lights. This allows them to be placed closer to plants (within a few inches) greatly decreasing lumen loss from the bulb to the plant. It is recommended that these lights be placed no more than a couple feet from the plants for best results. 2700k to 3000k bulbs provide higher output in the red spectrum which promotes flowering. 5000k to 6500k bulbs are full spectrum with much of the light in the blue spectrum which promote overall green plant growth.
The standard T12 bulbs full spectrum tubes are fine for starts and seedlings and are popular for growing low-light plants like herbs and African violets. These lights are inefficient and are be replaced with high efficiency T5 lights which are a better light source for flowering and budding applications as well.

[SIZE=+2][SIZE=+1]Incandescent Plant Grow Lights [/SIZE][/SIZE]​

These lights are the most inexpensive to purchase but are also the most inefficient and a poor source of light for plants. At best they can provide supplemental light to individual house plants. Incandescent lights have a low lumen output per watt compared to HID and fluorescent grow lights. New smaller CFL grow lights like our 40 watt Green Thumb system produce as much light as a 150 watt incandescent bulb, and more of the light is used by the plant. This type of bulb will pay for itself in energy savings the first 60 days of use.​

[SIZE=+2][SIZE=+1]LED Plant Grow Lights [/SIZE][/SIZE]​

LED grow lights are the newest lighting option for plants. They are advertised to be the most efficient and coolest running grow lights available. We have tested several different types of LED grow lights and have found none that outperform much cheaper fluorescent grow lights of similar wattage. LED plant grow lights are also not recommended for use with plants that you want to be viewed, because they give plants an unnatural appearance when the light is on.​

[SIZE=+2]Light Output Comparison Chart[/SIZE]

Each scenario above represents approximately 50,000 lumens.




[SIZE=+1]Heat Output [/SIZE]
The chart above uses a combination of the light bulb temperature and the dimensions of the bulb(s). Bulb Average Bulb Temperature . Bulb Average Bulb Temperature T5 100 to 120° F Incandescent 220 to 260° F CFL 130 to 180° F MH/HPS 450 to 550° F

[SIZE=+1]How Long Should Grow Lights Run?[/SIZE] This depends on the type of plant. Foliage plants need about 14-16 hours of light per day. Flowering plants need 12-16 hours of light per day. You should give most plants at least 8 hours of total darkness daily. Try to have the lights on at the same time every day. You can get an automatic timer for your lights to make it easier. [SIZE=+1]

The Electrical Cost to Run a Grow Light System [/SIZE] To get the operating cost per hour for a light, take the lights combined wattage, and divide it by 1000 to get the kilowatts used. Then multiply that number by the amount your electric company charges per kilowatt hour. HID lights will use the number of watts it emits per hour, ie; 600w system will use 600 watts per hour (regardless of spectrum).
(light wattage output / 1000)x electricity cost per kilowatt hour= Operating cost per hour
operating cost per hour x hours used per month = Operating cost per month

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[SIZE=+2]How the Sunlight Affects Plant Growth [/SIZE]

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[Muddy]

Good info JM, but IMO the LED info is out of date and misleading.

 

[JM]

agreed... i was mostly after the HID / cfl comparison for new growers etc.

 

[AndyBotwin]

Thanks, JM - good general overview without getting too technical. I've found that the same wattage of T5 delivers far superior growth to equivalent CFL, and I believe that's mainly due to the bulb shape. CFLs are meant to disperse light outward to illuminate an entire room, so even if you have a good reflector, you experience significant lumen loss from the parts of the bulb that don't face directly at the plants. The cylindrical shape of the T5 bulbs allows at least 50% of the light to directly reach the plants, and the other half can be reflected downward very efficiently. I was shocked to see better veg growth from my 92w T5 fixture than I previously experienced with my 168w CFL rig.

Also worth mentioning is that CFLs contain a ballast in the base of each bulb, greatly increasing the heat output when used in large quantities. T5s have ballasts in the upper part of the fixture, ensuring that the majority of the heat output will rise upward rather than being trapped under the reflector near the plants.

 

[Muddy]

I thought so. I just wanted to throw that in so anyone reading it would be aware. I think I have the same article linked in the Reference Links forum. I also put a note about LEDs in there as well.

agreed... i was mostly after the HID / cfl comparison for new growers etc.

 

[JM]

very well iterated andy! :thumbs: I totally concur.... yeah, you wouldn't believe all the little transformers and stuff in thos little cfls or the big ones... lol all heat loss... or gained in a closed room... lol

I use a lot of regular 48" fluros for starts in the spring and stuff... i agree... they deliver light right were you want it... not spread off in all crazy directions... I drop my 4 foot fluros almost to touching.... I've never had a T5, but I've seen what they do and have no doubt they deliver well!

:smokebuds:

 

[realcarlos]

Mr. Botwin
Do you know who where one could purchase a decent T5 system for a decent price?
Room area is
4 feet length
2 feet wide
5 feet high

 

[slightlystoopid]

The quantum bad boy would fit perfect
http://www.plantlightinghydroponics.com/quantum-badboy-t5-4ft-lamp-grow-light-p-3353.html

 

[AndyBotwin]

The quantum bad boy would fit perfect
http://www.plantlightinghydroponics.com/quantum-badboy-t5-4ft-lamp-grow-light-p-3353.html

Yeah, the Badboy fixtures are great. If the 8 bulb fixture is a little tight in your space, they make 6 and 4 bulb versions that are narrower. If you're looking for a more affordable option, I've had good experiences with the Hydrofarm fixtures that can be found at Amazon or most hydro sites.

 

[realcarlos]

Thanks bseal and andy.
I was looking for something that creates the least heat. I can't really make holes in the walls/doors for fresh air but can leave the doors open for a bit

Would a 4bulb T8 (shop light 4 34 watt) along with 5 23 clf bulbs for a plant or two? in that area?

Now all thats needed is a reliable ph meter