How far sould my 400W MH be from seedlings?

[steeders]

how far should my 400w mh be from my seedling ive looked at lots of threads about this and everyone talks about hps distance but nothing about m/h is it just the same as hps?? distance and heat wise??

 

[Dan Ultra]

MH puts off more heat than HPS, so you'll want it a little further away. I started my MH at 50% and 10" away and had no issues. I maintain it at 10" now, but at 100%. There is a chart somewhere on here that has safe distances. I will see if I can find it for ya

**edit** FOUND IT This is for sufficient light and does not take into account heat, so lean towards the safer end of the distance and slowly move down your light if you see too much stretch. Like I said, 10" was safe for me

 

[steeders]

that would be great thanks man (",) unfortunately i dont have have an adjustable ballast so il just put it a bit higher than 10"
(",)

 

[Dan Ultra]

Updated my post for ya

 

[steeders]

perfect man thank you for that il be taking it easy to start with like i only have 3½ft from top of pot to bottom of bulb so i will have to learn to lst my plats so thats what i need to read up about now thanks again m8 (",)

 

[steeders]

i knoe there is light charts for hps distances but thats for established plants what about seedlings that are 1/2 days out top of soil 10" for 400w is a bit extreme but no one has an answer my mh bulb is just to hot temp shoots up to 31°c so im back using the duel spec hps some one give me a straight answer please ?? before it's to late many thanks in advance (",)

 

[NuttyProfessor]

Re: someone please help??

i used a 600 watt with seedlings i kept it high , i also made sure they didnt dry out , as the plant grew i lower , but if its really freaking you out get some cfl for them then you wont hurt

 

[Weaselcracker]

I have my seedlings, which are currently about 4" tall, about 24-30" away from the 400 mh. However ,I've tucked them around under the edges of some larger plants next to them. Growing perpetually I always do it this way and it seems like a natural state for a seedling to be in - shaded by it's companions. This allows lots of ambient light and I feel that it lets the seedling have some 'choices' about whether it wants to shoot for the light or hang back in the shade, instead of being totally exposed in the glare. So maybe that's an option for you- or to toss in a houseplant to grow a while, or shade cloth, or some other mild shade source . Just ideas.

 

[steeders]

thanks for the quick response (",) i have my bulb at 3ft fro top of the soil to be safe do you think thats to far away? 30" is 2½ft would that be better i have good airflow and a fan pointing at them my temp sits around 25/27°c should the fan be pointed at the bulb or just above the seedlings?

 

[Weaselcracker]

I'm guessing anywhere in the 30-36" range should work and be playing it safe. Someone else can probably give a more specific answer. Just keep an eye on them. You won't go too far wrong. Once they start growing true leaves they will need more light. Or if they seem way too spindly and tall they are too far away- but I dont think you'll get that problem as it is.
Put the fan on lowest setting and definitely on oscillating (back and forth) and put it several feet from the seedlings. If for some reason you don't have an oscillating fan- or if it seems like it's blowing your seedlings sideways too much right now, point it in some other direction away from the plants -like aimed off in to a corner.

 

[steeders]

thanks bud thats what i will do and take it from there (",)