Hey guys, when I germinate my seeds and let them grow, what required light is necessary for them? I have a 400W light and that's it, I know this will work but is there any other more cost efficient methods?
I find that my 400W is not suitable for seedlings. They always seem to stretch uncontrollably. I veg under (6) 4' t8 florescent tubes they are only ablout 23W each. I cover a 2'x4' area with only 138W. They get me entirely through veg. You could also pick up some CFL's and fixtures relatively cheap.
I have the same question. Bump'd for more replies. edit: to add onto what grrower said. I have two t12 lighting fixtures that hold two florescent tubes @ 40watts each. Would they be a good substitute to get my seedlings started (and also to get my clones rooted) until they are ready to be put into the grow tent under the 600w mh conversion bulb for veg?
What he said, and yes t12s will work fine but not quite as effectively as t5s make sure you get 5500-6500 k bulbs for veg.
Give a man a fish... Lets do some math. 4 x(t12 Floro 40W @ 2000 Lum. Ea.) = 8000 Lum over an area of roughly 2' by 4' @ 2' high run 24h/day(for a clonery). Light Light diminishes based on the Inverse Square Law. (Here's a handy calculator for the lazy)Use the manufacturers number as I1 and d1. The Lumen level of lights is based on a distance of 1' from the bulb. 4x(40w T12 Flo) (2000 x 12)/22 = 500 Lum. @ 2ft. x 4 lightbulbs = 2000 Lum. /(2x4) foot growspace = 250 Lumens / Sq. Ft. @ 2'. Juice 1kwh (Kilowatt-hour)= 1000 watts per hour 40w bulbs * 4 = 160w * 24 hours = 3840w = 3.84kwh/day So it takes 3.84 KwH per day to give a 2x4 foot space 250 lumens for 24 hours with 4 40w t12 fluoro tubes. Bored yet? No calculators on the Test! Put your books away. No talking! SIT DOWN and NO you can't go to the bathroom! alright. Lets look at a 400w HPS, same stats. assuming you have a vented hood and can grow 2' from the bulb. The only difference here is the bulb and the grow size. Obviously you wouldn't use a square luminare to light a 2x4 foot space, so we'll assume you've got a 4' square. It will mess with the overall calculations, but we're trying to make this a realistic estimate, not a textbook one. 400W HPS Light (55,000 x 12)/22 = 13,800Lum. @ 2ft. /(4x4) foot growspace = 862.5 Lumens / Sq. Ft. @ 2'. Juice 1 x 400w bulb = 400w/h * 24 hours = 3840w = 9.6kwh/day Ignoring the price of replacement bulbs/ballasts/starters what have you, ignoring upkeep, we're looking at this: Total 4xt12 3.8KwH @ 250Lum/Sq.Ft. Ratio: .015 KwH/Lum/Sq.Ft. 400w HPS 9.6KwH @ 862.5Lum/Sq.Ft. Ratio: .011 KwH/Lum/Sq.Ft. As KwH cost money...it's cheaper to run the 400w HPS for what you're getting out of it. 400w HPS vs. 4x40w T12 Flo's Lumens Ratio (862/250) = 3.448 (how much light) Watts Ratio (9.6/3.8) = 2.52 (how much elec. aka $$) Area Ratio ((4x4) / (2x4)) = 2.0 (how much space) While you'll be paying 2 and a half times as much to run the light, you're getting twice the growing area and more than 3 times the light in that growspace. You can conclude that you'll be paying more per square foot but will be gaining lumens at 73% of the cost of the Fluoros (2.52/3.448) ...teach a man to fish... -- The previous math doesn't account for light spectrum. If you're running a full spectrum bulb in your HPS you won't have as much issue with stretching as with a regular HPS bulb. Fluorescents work excellent for veg. Grrower brought up that point. It also doesn't take into consideration the voltage of a cooling fan, generally required for an indoor HPS light. It's based on bulbs I found online quickly. There are more powerful bulbs available. Mostly it was an example of the math so you may begin to calculate the specs for yourself. -- Chidy: I use 4x40w T12s for my clonery. It will hold 5 standard trays, which each will hold 16x4" pots, 32x1.5" pots, or 100+ rockwool cubes. More than enough room to clone weekly, and get veg going for a couple of weeks before I move them under the MH. Growth is good, heat is good, low wattage is good and the bulbs can grow up and touch the light without issue. Ive had one grow all the way into the reflector without any signs of slowing down or burning. -- GoGreen: Unless you've got a limited amount of vertical space, I'd stick with trying to get the 400w running. If you're doing a single "batch" harvest, you'd do well to use the HPS over cheaper alternative. You can add supplemental blue spectrum lighting (from CFLs or Flo tubes) to keep the stretching down, but I'd use the 400W as the main light. More bang for the buck.