So what I'm wondering is: can you plug a metal halide bulb into a regular socket? If not, is there any converter out there so I don't have to buy the whole shebang just yet?

Thanks

Do a search here and look into CFL's (compact fluorescent lamps). The really big ones are fairly expensive, but not as bad as metal halide, and they don't need a ballast.

I got a new 400w MH electroic ballast plus a bulb all for $50.00 on ebay. I spent another $10 for parts and made myself a fixture. Because it's an electronic ballast, it can fire both MH or HPS bulbs.

This system made a huge difference in my seed starting efforts.

dcarch

I have a passion vine, that I brought in from summer, the frost got it twice. I took a few cuttings and stuck the plant under the MH's, and now, a few weeks later, it is beautiful. It is getting ready to flower again, the leaves are deep lush green. It is nicer in my basement that it was outside, because there are no "elements" to damage it.

HTH let us know what you decided

good folks there with high quality and cheap prices. there you can get a 400 watt hps or MH for around $120.

i wouldn't even think about using compact floro bulbs cuz they aren't going to put out the power you need.

also i was wondering how many square feet you need to light. usually a 400watt covers 4'x4' , a 600 covers 6'x6'-8'x8' , and a 1000 watt covers 8'x8' - 10' x 10' area. so keep that in mind when selecting lighting.

Thanks.

(Lermer) Normally, you want to go horizontal in order to get as much direct light as possible. The light footprint is rectangular, and from end to end you get only about a 3' width. From side to side you get 4'-6' depending on reflector type. That is with a 400w.

Increasing the wattage does increase the horizontal coverage, but not the vertical coverage (which is limited by the canopy which blocks light to lower leaves). However higher wattages mean fewer points of light and more shadows on leaf surfaces.

Quartz metal halide (MH), and HPS, are hopelessly obsolete. I recommend either ceramic metal halide (CMH), or pulse start metal halide (PSMH). Fluorescents are fine for cuttings.

Eventually LEDs might be efficient, but by then probably something else will come along. I'm excited by the new 25 watt CMH with parabolic reflector bulb. At about one foot, there are 4300 foot candles (optimum). At about two feet, there are still 1000 foot candles (adequate). I would recommend many of the 25w CMH bulbs, but the problem is the high price on this new patented technology.

http://en.wikipedia.org/wiki/Luminous_efficacy

The price is higher, but the CMH (with PAR reflector built into the bulb)reflects better because the arc tube is almost a point source and it is horizontally oriented.

Without a parabolic reflector built into the bulb, the compact fluorescent radiates in almost every direction, and is not directed toward the plant.

The PAR CMH does indeed produce a highly focussed beam just like the halogen reflectors it is designed to replace, but this property is of only limited value for growing plants. In fact most growers strongly prefer a more diffused light to allow maximum intensity without localised scorching. Some form of reflector, baffle, or enclosure is important to getting maximum light from any bulb onto the plants. Some CFLs come with an integrated reflector, some don't, but something should always be used for plants. A simple device like a white card baffle surrounding the area is extremely effective.

And what is this about horizontally oriented. It is oriented whichever way you plug it into a socket. It is in fact vertically oriented with respect to the reflector, a choice which is equally as effective as any other orientation when combined with an appropriate reflector shape. In this case, the vertical orientation with a round reflector gives a symmetrical beam spot, highly desirable for this type of bulb.

I own a 1500w metal halide but it doesn't really do all that great for growing plants (5200k).

The best solution I've found for me, and what I have used for the last 15 years, is a home made setup... and is definitely not up to code.

I use a scavenged (from a demolition) Dual T12/HO 800ma fluorescent ballast- but used with two 100 watt(800ma), red phosphor mercury vapor lamps in reflectors instead of fluorescents. Like I said, I've used this setup for years without problems (like ballasts catching on fire or exploding lamps). I actually metered the voltage drop across the bulb and also made sure the current supplied was 800ma, and calculated that the lamp wattage was closer to 120 watts/bulb...so about 240 watts total. The ballast does get hot, but not too much so. Not all mercury vapor lamps are the same. The best, locally available, come from home depot and have a red phosphor (and will glow pink/red while warming up). Those with low color temperatures can be ordered but cost more.

I use an upstairs junk storage room with a blanket over the window (I've been through the police banging on the door at 1am)... so forgive the mess.
Basically ONE yellow to ONE blue (just one but doesn't matter which)... just tape off the extra blue, and the other yellow to ONE red (just tape off the extra). Just don't be stupid and short out the two yellows or blues or reds.....

Bulb while warming up....

...and in use.

I bet that is because your MH bulb is deficient in far red light which increases photosynthesis via the Emerson Enhancement Effect. You can determine whether this is the case by performing an easy experiment. Supplement your MH light with a 100 watt incandescent (regular) light bulb in one of those clamp fixtures pointed close at one test plant. I suspect that the growth will more than double. Incandescent bulbs are rich in far red but, for a more permanent setup, a more efficient supplemental source of far red is Philips White SonŽ Bulbs

Otherwise, special MH bulbs with ample far red output are available. They include Philips CMH 4K and EYE Hortilux Blue.

I have both...And the plants under the "halide" are so amazing, that I take the ones out from the compac florescents, which I still paid a high price for, just to give them a boost.

Have you ever been in a room with a halide light on in dead of winter?
It is like summer time in there, in full sun..By the way, is it possible to get a tan under these? lol

No, because the UV doesn't pass through the outer glass bulb. The inner tube is quartz which passes UV. If you break off the outer glass bulb, I suspect that there would be much more UV than is in sunlight and it would be a health hazard to you and your plants.

I'm trying to find a ballast that can do this but I'm not sure what to search for.

You are absolutely correct in this. I found I had to supplement it with at least a 300 watt halogen, and preferably a 500 watt (in the past). My problem with it all was pulling 1800 watts on a standard 120 volt circuit... (house built in the 20's, cloth wires on spindles underneath the floors). I don't trust it for fear of being a fire hazard. For this reason, I prefer to have a lower wattage, all encompassing type lighting method. I'm NOT fond of grow bulbs that utilize sodium to get low color temperatures. The yellow/green light from sodium is in the least plant photoreactive sensitive part of the spectrum. I'm still waiting for some bulb manufacturer to come out with a good lithium iodide horticultural lamp.

1. Nobody knows exactly how different wavelengths of light interact therefore photosynthetic action spectra, which are measured using monochromatic light, are relatively useless for selecting bulbs.

2. Even so, many photosynthesis action spectra show that green light at 550 nm has about 33% of the activity of the peak which is usually in the blue region. 33% is substantial and should not be ignored. Also, in a highly reflective environment, absorption of green light by plants is increased thereby increasing the green's contribution to photosynthesis.

Like I said, the best ever for me was a 2000k, High color rendition, 400 watt metal halide. But the lamp life was 1/3 that of a normal lamp. I can't find it anymore. The closest I can find is this:
http://cgi.ebay.com/2000k-400W-Aquarium-Fish-Tank-Metal-Halide-Bulbs-NEW_W0QQitemZ350261685529QQcmdZViewItemQQptZLH_DefaultDomain_2?hash=item518d392d19
Mine was phosphored and put out a very warm white light similar to that of an incandescent.

Most normal metal halides put out a harsh blue&green light that without supplementing red, is not all that suitable for growing plants. Horticultural lamps try to supplement the spectrum but shorten lamp life by doing so.

That said, I've yet to find a metal halide horticultural lamp in a 1500 watt rating.

Like I said before, Philips White SonŽ Bulbs has a spectrum that is nearly identical to that of incandescent but is 3 times brighter. The part of the spectrum that is important for supplementing regular MH is far red, 700 to 800 nm, which is practically invisible and therefore does not affect the color temperature.

Jury's still out on the rosemary, and the basil is so-so but I think with a couple days to adjust it will perk up.

Any tips I should know?