How close

Right how do i explain this.

I have four plants which are 6 to 8 inches high and the same in width(veg stage),,in a flood and drain with a duel spectrum 400 watt hps.

But the plants are in a open space , a COLD open space, but i do have my res heated.

And they is enough heat coming off my lights as well.
I suppose i have a few questions here!!

How close should i have my lights to the plants i have no fan at the moment.But i,am getting a moving fan tomorrow.

And also when i switch the lights it will be on for 12 hours of the day
will they be enought heat just with the res heated or will i need a heater fan aswell.
When i do switch i will have the lights on at the night time because of the temp drop in the room.
So the temp in the room could be anywhere between 7 c and 15 c.
Is this ok?

well i hope i have covered evrything there.

Thanks inadvance cron

thats pretty cold man.. ;(

croniccrag said:

I have four plants which are 6 to 8 inches high and the same in width(veg stage),,in a flood and drain with a duel spectrum 400 watt hps.

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Firstly, there's no such thing as a 'dual spectrum' HPS bulb - they don't just output two spectrums. I know resellers call them that, but it's misleading. It's a HPS bulb with enhanced blue spectrum, and it's still not great to veg under regardless of it's enhanced blue output.

"How close should i have my lights to the plants"

For a 400w HPS, no closer than 18 inches - 2 feet.

"And also when i switch the lights it will be on for 12 hours of the day will they be enought heat just with the res heated or will i need a heater fan aswell."

You need a heater.

"So the temp in the room could be anywhere between 7 c and 15 c. Is this ok?"

No it isn't. Your temperature needs to be between 24 - 28c with no more than a 16 degree drop between lights on temperatures and lights off temperatures.

its ok to veg under them, i have a 400W HPS (Blue Spectrum) and they grow clones perfectly.. you just cant put the light too low for the first week, and gradually lower it.. works fine.

yeah too low n you'll burn n shock the wee ones lower the light gradually and they will love you for it

thanks alot folks some good advice there.

tetrahydrocannabinol said:

its ok to veg under them, i have a 400W HPS (Blue Spectrum) and they grow clones perfectly.. you just cant put the light too low for the first week, and gradually lower it.. works fine.

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I didn't say you couldn't veg under them, I said they're 'not that great' to veg under them. If you want stretched, lanky plants, with wide internodes - you just carry on vegging under your HPS. If you've ever seen the results of vegetative growth under MH or 6400k fluorescents, you wouldn't think HPS was too great for veg either.

Yeah I agree with Babygro, I would only use hps in veg if that was the only light I had. Mh is the best for veg I think.

Hey, lots of growers have only one bright light. In the '80s everyone used Metal Halides, cause that's what was available on the consumer market. And the only reflectors were china hats.

I think it might have been that way because the MH lamps could only be postitioned vertically, and when sodium lamps came around with horizontal orientation, the growing reflectors came out that way, too, as it was better lighting for growing areas, and the HPS came to be known as the better lumen producer, so it was the lamp to pick if you only wanted one.

But I digress ... what was the question?