Metal Halide grow lights are Just like high-pressure sodiums their not all equal, some have more of the light spectrum needed for plant development than others, like the Hortilux bulb that?s mentioned below, so don?t be fooled into buying the first bulb you find,because of the price, because, remember ?light is life? it would be a shame to get everything right, only to end up the bulb you bought restricting your plants growth.
? Metal Halide grow lights
Metal halide grow light, lamps are the best for producing a strong output in the blue spectrum, which is the part of the spectrum that promotes strong vegetative plant growth and generally all round good growth.
Metal halide lamps can be used for the primary light source for growing plants from start to finish, such as lattice, tomatoes and cucumbers, although fluorescents are better for cutting and young plants, for flowering or fruiting, high pressure sodium lights are better as they match the late summer sun spectrum as the spectrum is more in the orange to red spectrum.
That being said, MH lights are still less than ideal for grow box applications, were it?s the primary light source because their light is predominantly greenish/pinkish in quality and thus produces less photosynthetic power, than the lamps actual electrical wattage or lumen (visible light power) output that would indicate.
? Don?t wait till its to late
Replace your lamps before they burn out! Sodium and Halide lamps gradually get dim over time and do not operating efficiently. When replacing a lamp you must use only the lamp made for your system. These bulb puts out 36,000 lumens from a 400 watt with a Color Temperature of 4000.
? Avoid the burn
Heres a general guideline on how close to keep the tops of your plants canopy from the bottom of your metal halide indoor grow lights. A good indoor/outdoor garden thermometer will help you determine if you can go closer or need to stay farther in your own set up. But by far the best way to determine the distance is to place the back of your hand (dorsum) under the bulb, and see if your hand feels ok, after a minute or two, and if not, neither will your plants.
? 250 watt light......10 inches
? 400 watt light...12-14 inches
? 600 watt light...16-18 inches
? 1000 watt light.....24 inches
As you can see, the higher the watts the further away your bulb will need to be, so some of that you gain with a large metal halide bulb, you loss with having it further away.
Using an air cooled reflector like my coolshade, that?s the trade name of my reflector, pictured below, will eliminate problem heat damage, caused to plants by bulbs being placed to close to plant canopy.
? So how many lumens for my watts?
Metal halide grow lights aren?t as efficient as HPS bulbs; they produce a little under 80 lumen's per watt, the further away the bulb is to the plant canopy. , But typically from a 400 watt you?d expect 45.000 to 50.000 lumen's from a MH bulbs.
? Can my plants absorb all the lumen's I throw at them?
Well short answer is no, lumen is a measurement of light for us humans, of what we pro sieve as bright light, but its most defiantly not a measurement that you?d use for plants as a large part of MH spectrum is in the blue, yellow and green, the same part that plants largely use for growth, blue being the bulk of what plants use for growing.
THEIRS A MUCH BETTER WAY TO MEASURE PLANT LIGHT
? Photo synthetically Active Radiation (PAR)
Photosynthetically Active Radiation (PAR) is a range of light wave length, that?s between 400-700nm, this is the lions share of what plants can use for photosynthesis Of the 3 methods most commonly used to measure light (Lumens, Lux , PAR), PAR is the most scientific way of determining a light source's ability to drive photosynthesis. It?s the closest measurement of light that we have that corresponds specifically to plants, so when a shop tells you next time, how many lumen?s a bulb has you no what to tell them.
?PAR is the most scientific way of determining a light source's ability to drive photosynthesis. It is the only measurement of light which corresponds specifically to plants?
HERE?S Photosynthetically Active Radiation (PAR) GRAPH for plants.
? Is there a way to convert lumens to PAR..
No afraid not, its like trying to convert an orange to a pineapple, which is never going to happen..teehee.Lumens is a measurement of visible, perceived light output, of that looks bright to us lot, where?s PAR is Synthetically Active Radiation. A lumen can have 0 PAR depending on the spectrum of light it emits.
A better way of providing just the right amount of the light that?s needed would be to use LEDs, only theirs so much hype surrounding led grow light, I thought I?d make my own at work, so if you have time on your hand, then follow along and if it really works I?ll follow up with a how to.
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