What size plants w/ 400w hps?

Hey guys, I just got a 400w xtrasun hps and I was wondering how good the penetration is, or just what height plants I can successfully achieve with this. I've been using a 4 bulb t5 and I got one up to 2 feet with maybe a quarter oz or so with all the other supplemental cfl lighting, I'm thinking about trying to fit 12 plants in a 4x4 area would that be okay or too many? Most of them are from seed and short trees, but I have some mini shrubs too lol. Feel free to ask any questions, fyi I'm growing in ff oceanforest soil, 3-5 gallon pots, and vegging with a t5. I don't really pay attention to the age of plants until flowering but I veg for up to a foot or so. Peace.

I'm running 5 plants under 600w, I think 12 under 400w is a bit much. Good luck with your grow

12 is too many unless they are tiny.

dood i just got 4 going under my 400. unless your gunna grow 12 small ones ins a SOG set up

I've got 3 under my 400. When I go for 4 it gets too crowded but I only have 12 sq ft you have 16... I'd go for 4 plants if I were you

What do you guys call small? Cause I call my 2 foot one small, I'm growing in the homebox XL and iit's in a 5 gallon bucket and I could easily fit 11 more of that same size. All I'm simply asking is how much penetration a 400w hps has. I also have like 10 cfls that I could stick on the bottom side. I'm not trying to go past like 3 1/2 feet, I think that's relatively small. Plus I'm keeping the light about 2 feet over the plants due to heat issues and the lights footprint is the bigger than my 4x4 area. So what's the penetration on it, or what do you consider a "small" plant.

Plus I've managed to grow half a closet full with just cfls up to a foot, I'm sure my hps can give me a lot better results than my cfl closet grow.

bajafox said:

I'm running 5 plants under 600w, I think 12 under 400w is a bit much. Good luck with your grow

Click to expand...

how big are your plants?

easiest thing to do to figure out how much light in Lumens you are getting at the bottom is to measure the distance to the light, and then apply Inverse square law. You should be able to very easily figure out what you are getting. just take the total lumens of your light, distance from light to desired area and run the numbers through the law.. You will be amazed at how little light you are getting after you are 2 ft from the bulb...

The reason we were suggesting fewer plants was because of the penetration you're asking about. Sorry I didn't explain myself last post... The plants will grow much faster under the hps ligh than your fluorescents. The penetration of the light is good when the plants are young... But when they grow they getthick and the light won't penetrate very well at all. Especially not with that many plants. If you wanna try to bud just the tops of 12 plants or the entire plant of 4 plants you'll probably yield similar results. Though different people will tell you different things. If you've already got the plants then go for it but know you'll pretty much only be growing the tops Because of the reduced penetration due to thick vegetation

I guess I'll just learn from first hand experience on this then. Thanks for the lumens formula. It's not that I'm trying to stick so many plants in the area, as much as I'm legal to grow 12 mature plants. I'm trying to take full advantage of that number. I will let you guys know how it turns out.

Thanks for all of the input guys.

for a 4'x4' area you need a 1000w light

400w does a 2'6"x2'6" area
600w is 3'x3'
1k w is 4'4'