A person holding up some lettuce in front of a row of plants.

Lighting FAQ’s Part 1

Q. Which is a better lamp to grow with MH or HPS; Im on a limited budget and can only afford one?
A. I would recommend purchasing the Metal Halide kit, and when it comes into the bloom stage you purchase an HPS conversion lamp or a full spectrum MH lamp. If you are only going to use one type of bulb for flowering and vegetative stages the Sun Master neutral deluxe is an excellent lamp for both purposes. This will be more economical for setting up on a limited budget.

Q. How long does the average 1000 watt HPS lamp last?
A. On average they burn for 12000 hrs but most gardeners replace once a year more maximum efficiency from the lamp. The cost of new bulbs is minor in comparison to yield loss from weakened lamps. The best way to monitor a bulbs wear is with a light meter. These can be expensive, any where from $100-$300, but for a larger scale set up it is wise investment.

Q. Is it worth the investment to upgrade to a full spectrum bulb rather than the standard bulbs?
A. While the standard bulbs perform very well, I have seen first hand the benefit of full spectrum lamps such as Hortilux, Solarmax and Sunmaster and can say with confidence these lamps are definitely worth every penny. But if you are on a limited budget and you buy the clears you will still get excellent results as they are still a very high quality lamp. The full spectrum bulbs give you a combination of red and blue light similar to HPS and MH mixed together which is best for optimum growth.

Q. Which Bulb should be used in the Vegetative stage and which one in the bloom?
A. Use a Lamp with a high output in the blue range of the spectrum for the vegetative stage and for the flowering stage use a lamp with a high out put in the red range of the spectrum. During all stages of growth but especially during the bloom stage plants require a balanced mix of blue and red for optimal growth.

Q. Based on Lumen per watt Ratio what is more efficient to operate, MH or HPS?
A. HPS gives a higher lumen per watt ratio than metal halide and the bulbs often last up to twice as long. The 600 watt HPS has the highest lumen per watt ratio of any HID bulb. But for growing MH has a higher PAR value than HPS but often isnt enough in the red range of the spectrum, this is why a mix of both is required for optimal growth. Or the use of full spectrum bulbs is replacing mixing the MH with the HPS. The bulb manufacturers are doing this for you.

Q. Can I run a 1000 watt MH bulb wired up to a socket and just plug it in my wall plug?
A. Absolutely NO, NO and NO!!! You have to use a 1000 watt MH ballast to power this lamp. The power coming out of your wall must be transformed to usable voltage by the lamp. This is the job of the ballast.

Q. What should my light cycle be for growing indoors?
A. Since plants all have a different requirement of light that will depend one what type of plants you intend to grow. The best thing to do would be research the plant you wish to grow and find out its light requirements. Most gardeners use an 18 hours of light, 6 hours in the dark cycle for the vegetative stage and a 12 hours of light, 12 hours of the dark cycle for the blooming stage.

Q. What is a Lumen?
A. A lumen is a measurement of light. In simpler terms one lumen is equal to the amount of light that 1 candle will emit on 1 square foot, 1 foot away from the flame. 1 lumen = 1 foot candle

Q. What is Lux mean?
A. Lux is the metric unit equal to the amount of light falling on one square meter 1 lumen = 10 lux A lux is only 1 / 10 th of a lumen

Q. What is the average lumen per watt ratio of an HPS and MH?
A. HPS  140,000 lumens per watt MH  100,000 lumens per watt Fluorescent  83,000 lumens per watt Mercury Vapor  63,000 lumens per watt Incandescent  17,500 lumens per watt

Q. What is the definition of PAR?
A. PAR stands for Photosynthetically Active Radiation

Q. What is the PAR value?
A. PAR value is the amount of light usable by the plants

Q. When the lights are off whats going on with my plants? Obviously they dont just sleep so what do they do?
A. In the dark cycle the plant shifts its focus from leaf production to root production. The leaves transfer extra stored energy down to the branches and roots. The plants dark cycle is very important. 24 hour light cycles are not the way to go despite radical theories and tests.

Q. How high should my lights be from the tops of my plants?
A. The lamp should be 18  24 inches away from the tops. Use an oscillating fan to circulate air on the tops of your plants. This will help with the removal of heat produced by your lamp and also deliver fresh air across the undersides of your leaves which are where the plant breathes in through tiny microscopic pores called Stomata.

Q. What is the Kelvin rating on a bulb mean?
A. Kelvin is the unit of measurement expressing color temperature. Each lamp has an aggregate Kelvin temperature that indicates the bulbs spectral output. For indoor gardening a bulb with a Kelvin rating between 3000-6000 will be sufficient

Q. Can I use a green light in my grow room in the dark cycle? Ive heard that green light wont wake up my plants?
A. Yes you can use a green light in your grow room. Plants do not respond to the green range of the spectrum.

Q. What is a more efficient reflector to use if my lamp is universal, horizontal or vertical?
A. Definitely horizontal. Horizontal reflectors can reflect up to 40 % more light back down to the growing area. The light form a bulb is emitted form the arc tube located in the center of the lamp. If it is burning in the horizontal position, half of this light is being directed at the plants while the other half is being reflected back down form the reflector giving a complete distribution of the light. If the lamp is burning in the vertical position all of the light goes out the sides and had to be reflected back down minimalizing the intensity being directed at the growing area.

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