Hey, i was wondering how far the distance of HPS lamps, 400 watt, should be from plants throughout the grow process. I am just starting now, what should my seedling distance be, vegetative and flowering distance. i am going to use the hps light the entire time.

I was told always 12 inches but no further than 16

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RIU AUTO-FLOWER CREW
Current Grow Sea of Ryders

I'm using a HPS for my whole grow, and my light is about 16 inches from the plants. They are currently in the seedling stage and looking very good. Just put your hand under the light if it's too hot for you, it's too hot for the plants. As far as the vegetative, and flowering I don't have an answer yet. Good luck.

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I tried to clone a four leaf clover, no luck.

Best rule of thumb for lighting is to put the back of your hand above the tallest part of the plant for a minute or so if your hand gets hot the light is to close. Also remember that your plants can grow several inches in a day

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I have never grown marijuana or intend to. Anything I post is knowledge gained from reading, not personal experience. Any pictures I post were aquired on the web or are fakes.

my husband and I are using a 400 hps for our first grow also. we have two that are 2wks and 11 that r 1 wk we had the lamp to close at first n sort of scorch the leaves, when we realize this we moved it up to about 10 ins to see if that help, yes it did. they began to grow again n open up whew they survived. now the lamp is about 12ins from 2wk olds and 15ins from seedlings. just watch ur plants, they will tell u when something is wrong remember the light is a good one, so keep it high.

According to Jorge Cervantes a 400W HPS puts out 50,000 lumens at one foot and at two feet it puts out 12,500 lumens. He recommends between 12 and 24 inches. In his newest grow DVD he was saying 18" and all of the gardens he showed looked like they were doing well at 18 inches above the plants. I have been keeping mine at 18 inches and my plants have been doing well. I guess the size of space you have and how well ventilated it is will be a factor as well.

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Ganjafarmer
http://www.rollitup.org/grow-journal...lood-grow.html

So is the heat from the lamp more important than the intensity of the light when it comes to burning up plants?

keeping a room/closet at a steady 73-80 degrees with a lamp a foot away is ideal . and a must is good humidity. spray the plants but careful not to hit the bulb.