Lights and height of plants.

[GreenRabbit]

Wondering...

I have 8 Foot Ceilings

Take away 2 feet for,

5 gal buckets and light fixture

Equals: 6 feet

I have a 600W light so the plants need to be 3 feet away so the will not burn.

Equals: 3 feet to grow a plant.

How do you guys get around this using 600W or more?

[Sativus]

you can get a little closer than 3 feet away. get a fan, its as important as anything else. i like to keep a fan blowing over the top of the plant and right under the light. i keep my lights about 6 to 8 inches away from the plants. hold the back of your hand under the light and feel where it starts to get warmer or hot. then gauge the distance to the top of your plant. adjust accordingly.

[GreenRabbit]

cool, what W do you use?

Also, if I veg till 2 feet, how tall will it be "AVG" when it is done?
I know it depends on the plant and what kind but on avg?

[Sativus]

a plant can stretch 2 to 3 times its height in flowering. so if your plant is 2 feet, you can count on it growing to 4 feet. i use about 600w flowering, same as you have. keeping the light a little closer also helps reduce stretching a little. just remember , if the light is too warm on the back of your hand, its too warm for the plant.

[dgann]

Listen when I tell you this. You will understand what I am saying. The "back of the hand" thing is not going to cut it. If you place your hand between your plants and lights and bring the lights down until they dont burn your hand you are causing yourself a huge heat problem. It DOES NOT WORK! Here is the reason why. Your hand can take more heat then the plant can. Even if the bulb does not BURN your hand, the temps are still too high. Usually they will run between 95 to 110 degrees. Pot does not like high temps. In a range from 76 to 78 degrees is about all. Here is a sure fire method of setting your lights. Hang the light. Take one of your pots and lift it SLOWLY to the light and you will see the intensity change. The top of whatever grow medium you are using in the pot will apear to be a lot brighter. Set your lights to that height and you will be done with it. That my boy is the best way to deal with 600 watt plus lighting. A fan does not hurt at any rate and can only be a benifit to your babies. Dont use the hand thing. Dont ask me why pot is so tempermental about heat though because it grows in some pretty hot climates. I suppose maybe thats where "outside" pot comes from dunno. Its hot in TExas in the summer, its hot on Mexico, it was REAL hot in Viet Nam and they grow some really gimungus plants over there bud. Matter of fact, so big that I have a pic or two of me standing UP IN a pot plant on one of its branches. HUGE pot plants but the temps are around 120 degrees with the relative humidity around 100 percent. Whats the difference? Dunno, except the outside varieties of pot might be the reason.

davyboy

[Zandor]

First you need an air-cooled hood. You can get a cool tube from eBay for about 125.00 usd or less if youâ??re lucky. With the cool tube you can get the light to with in 12" of your plants. 3 feet away is way to far you are loosing almost all the lumens and the plant is not getting the light it needs.

I use a remote temperature probe to monitor the heat at the top of my plants under the lights. Keep it below 85 at all times. Use a fan to move air around the room. IF you have a sealed room then you need to exchange the air a few times a day.