Daylight fluorescents simply means close to 6500 Kelvin, which looks similar to sunlight and therefore pleasing to the human eye. Plants like fluorescents near 6500 K, but they also like fluorescents near 3000 K. I have found that an even mix of these bulbs is best.

There are several types of fluorescents. Most people are using the 40-watt shop light fluorescents to rear seedlings, which are later moved outdoors. Advances in fluorescent technology have given birth to units like the 54-Watt High-Output and 95-watt Very High-Output fixtures. These fixtures are capable of fruiting plants to maturity without the sun at a fraction of the price and with lower heat from High Intensity Discharge lighting such as High Pressure Sodium and Metal Halide units. Therefore, an increasing number of hobbyists are taking advantage of HO and VHO fixtures to garden completely indoors. HO systems are more efficient than VHO's despite having a lower wattage. I have discovered that 4 to 6 HO bulbs are sufficient for starting an indoor planting regimen in a decent sized area.

It's not true, at least for seedlings. Last year I used HPS, CFL and regular fluros and they all worked fine.

If you look at bang for the buck, a combo MH/HPS 400-watt system costs $165 and produces 38,000 (MH) to 50,000 (HPS) lumens.

A similar price ($160) T-5 HO produces 20,000 lumens. The more lumens the better!

Mike

The combo MH/HPS fixtures cost more around $200-250, not including the cost of the 400-watt lumatek ballast, an MH bulb, an HPS bulb, replacement bulbs, the glass shield, lamp cooler fan, other accessories, adapters or anything else you may need.

You're also emitting a lot of heat with MH/HPS and growing in restricted spectrums. Compare the spectral output of using either MH or HPS alone vs an equal mix of 4 cool white + warm white HO-T5 fluorescent fixtures and bulbs which cost a total of $100 or less. An 8 bulb HO-T5 would emit more than 1 MH bulb at 38,000 and still cost less in both final cost and electricity consumption without any of the extreme heat.

Rob,

The price I quoted was for the entire system: both bulbs, reflector and ballast. I don't need a cooler, glass or other accessories. The prices for the HO came from here. And the math: Eight 54-watt bulbs will consume 432 watts which is more than 400! Lastly, I don't get the extreme heat - I can hold my hand palm down less than a foot from the bulb and barely feel any heat.

Mike

Home Harvest charges a lot for their grow light materials. I searched many places and some of the cheapest sources come from yardlover.com and hydroponics websites like 4hydroponics.net

The most basic convertible combo system with all the bells and whistles is $335 and listed on homeharvest.com:

http://homeharvest.com/hydrofarmXtraSunStdBulbConv.htm

They list these convertible units as Premium, Deluxe and Budget. That's the budget version and it sucks.

I don't see any advantage to HID lighting other than having more lumens in one bulb.

Scientific studies have consistently proven them inferior.

That is a lie. See:

If I was running an enterprise growing indoors, where I wanted to maximize my profits, I would base it on the cost per lumen of lighting, taking into account PAR, on a yearly basis. One can easily amortize the cost of replacing bulbs, ballasts, etc.

You can do the math; HO is not as efficient. Here is the page listing the price of the HPS/MH 400-watt system. If you want to pay more, you are welcome to!

Mike

I realize that MH emits more lumens, but break it down... You get 95 lumens per watt with a 400-watt MH bulb to equal 38,000 lumens whereas you get 92.5 lumens per watt 54-watt with a single HO-T5 bulb to equal 5000 lumens. HO-T5's are more efficient; you just need more of them to boost the lumens to the 20k-40k level, respectively. At $11 a bulb, decreased electricity costs, decreased overall costs, decreased heat emissions, etc. I'll take an HO-T5 unit over a MH unit anyday.

Your link shows a very basic, crappy MH unit. If you go to the purchase screen, it allows you to add on to the basic model which ends up costing @250 for a decent system with an outdated magnetic ballast and the most basic HPS bulb. Research them a little more and you'll see what I mean. Otherwise, you'll be using a unit that was comparable to one used 20 years ago.

Rob,

I'm using the system that doesn't include the MH bulb. And please, tell me how 92.5 lpw is more efficient than 95 lpw. Or how using 430 watts to produce the same lumens is more efficient. Or how spending $320 is more efficient than $170?

You're sold on T5 HO and that is fine; I'm not sold on any particular type of bulb. Rather, I look at the cost to buy and operate it to get the best production.

YMMV,

Mike

Wow! Can you say Hijacked?

Anna the statement is not true. I grow many plants under 4' 5000k T12s and 21" T5s.

If this thread is still active, advice please: Putting comparative cost aside, and focusing on aesthetics in the house and ease of securing bulbs to a PVC frame (not ceiling) for a 3'x3' indoor pepper growing area, wouldn't a single 600 watt HPS HID make more sense than multiple fluorescents? If I were back in the midwest in my basement I wouldn't care how many bulbs I strung up, but in a house I am leaning toward the simple one bulb HPS solution which I can chain to a homemade frame (not drilling holes in the ceiling)

My 600 watt HID (I'm running MH, not HPS because tomatoes don't need the HPS color to fruit) and it hangs from two very small eye hooks - but in wood, not drywall. I completely covers a 3x4 area. The HPS bulb would do a 4x4 or 5x4 area.

Mike

We have setup a 30' X 60' poly-covered greenhouse to grow vegetable through our long, cold winters (hopefully) and are about to start the electrical installation. Can someone offer some advice on the lighting that we should install? I am leaning toward 4' 8-bulb HO T-5 units. I don't know how many I would need. We will have 3 beds, approximately 40' long by 4 ' wide each. Also, how close to the beds should lights be hung as to provide adequate light for the plants (enough blue and red light for their growth and fruiting?) Thanks...I'm really kind of overwhelmed with so much info available. Eva

Eva,

I won't tell you not to try it but I can tell you my experience from last year. It was a comparatively mild winter (only a couple of nights did it dip to single digits) and I used a double layer of GH plastic so heating was mostly done via 1650 watts of electrical heat. The cost was under $150 per month for my 16x8' building. But the lack of sunlight was a killer, especially trying to grow tomatoes. I would have needed to add about 4000 watts of lighting and ran them for at least 14 hours per day. That's another 160 bucks a month. That was for 128 sq. ft. You're looking at three times that.

Now if you plan on growing only veggies that do not require a lot of light and temps at least in the low 50s, and this winter is as mild as last year, you might be able to cut your costs some but you are still looking at huge utility bills.

Mike

The bad part about T5s is that the fixtures cover a large area and they need to be relatively close to the plants so they allow even less of the suns light to get to the plants. HIDs can be much further away therefor allowing much more of the suns light to reach the plants.
If the T5s were hung on a retractable device that would allow for more sun but that would also be more work for you. Your utility bills are going to be much higher with either type of light but the initial cost will be higher with T5s.