Just one light.

I've got a desk lamp with a 20w CFL, some dirt, and some seeds. Will they even try to grow with just one CFL, or do I really need to invest so much money into lighting before I know if my seeds are dead?

You can get away with using the 20W bulb for a couple weeks before you'll need a lot more.

Are you looking for some buds or just to grow a MJ plant ?
If your looking to actually harvest some bud off that plant
you'll need plenty more where that came from. I would
say you need at least 15,000 lumens of florescent, Metal halide
or High pressure sodium.
Keep in mind 1x150watt HPS will give you that,for a total
of around 16,000 lumens.
100watt HPS= 9500 lumens
70watt HPS = 6300 lumens

Heres a look at florescent:

Standard philips 60watt= 4050 lumens
Standard philips 40watt = 3200 lumens

Mmmm...

I had gathered that the ideal lighting fixture was a 430w metal-halide lighting fixture [horizontal only type] for sufficient lumens and temperature spectra [similar to summer sunlight, apparently]. [Hard to get, and v-e-r-y expensive..!] And that the High Pressure Sodium fixtures work quite well, but tend to cause flowering early rather than vegetative leaf growth [which it is what I'm after, BTW], because of slightly reddish spectrum they put out, approximating the autumn sun light.

For me, compact fluorescent bulbs are easy to get and wire up. I presume IMHO, that if the above mentioned lighting fixtures cannot be obtained, then use as many flourescent bulbs as one's own timer can stand in its electrical rating [up to 2.4 kilowatts?], and physical room for them in the closet. Just a guess.

Any better suggestions?

just how far should my 500W lighting setup be form my plant?

I was going to use a 40w florescent blub for my 6' plant, but im using a 3" ballest I got for the first stage's

:) New grower's luck

Newgod-- as close as you can get it without burning the plant if your 500w setup is HPS or MH use a fan cause they cause lots of heat. you want to have a 70-80F temp.