Light to close?

[Brad]

I Have a 250W MH bulb how close will i be able to put this to my plants before they burn? i do have an extraction fan that keeps the room at about 24 Degrees.

Thanks

[Frazz]

Place your outspread hand, palm down at the top of the plants, if the back of your hand feels nicely warm then that is generally OK....if the light feels at all hot on the back of your hand the light is too close.

unless the plants are still very small, then increase the distance further

 

[Brad]

Ok so i have a total of 550cm between my light and the top of my pot, so my plan is to grow untill they are 350cm high then turn to 12/12 and hope they only grow another 100cm which will put them about 100cm away from my light. thats the plan anyway, but if they do start to burn as the get close to the light is there something that i can use to defuse the light? i have one 5 inch fan that comes on for 15 mins every 2 hours to exaust the het, but am i better to swap that fan around and make it blow around the air in the room?

Thanks for the help.

[Frazz]

well if they start getting to close to the light you can use plastic twist-tie's around the uppermost branches and attach them to string which can be tied to holes drilled in the rim of the pot and gently pull the branches down away from the light, also a small personel fan directing air between the top branches and the light may help

 

try to research any other grows of the same strain to try and find out how much stretch your chosen strain will give

all the best with 'em

[WantDaChronic]

unless you intend on doing some major lst after you turn them, they'll grow alot more than what you are expecting you should aim to have the plants fill up 1/3 of the space available and then turn them if you havent grown the strain before as some plants can more than triple their hieght after being turned, some like my mango sativa have grown about 5x as big since turning although doubling in size is more common, if grown from seed or the strain has a bit of sativa in it, you should still really only fill up 1/3 of the space

 

a 250w MH is a fairly weak HID and i would only keep the light about 40cm for starting out and once the plants are established and putting out semi decent leaves, you should take frazzle's advice about using your hand as a guide for how close to get the light to the plants...just remember that the further away the light is, it gets weaker and weaker you want to get it pretty much as close as you can without burning them which for a 250w light shouldnt be much more than 10-15cm imo, but remember to test it with your hand as every system is different

[torana2000]

Ok so i have a total of 550cm between my light and the top of my pot, so my plan is to grow untill they are 350cm high then turn to 12/12 and hope they only grow another 100cm which will put them about 100cm away from my light. thats the plan anyway, but if they do start to burn as the get close to the light is there something that i can use to defuse the light? i have one 5 inch fan that comes on for 15 mins every 2 hours to exaust the het, but am i better to swap that fan around and make it blow around the air in the room?

Thanks for the help.

i think you mean MM not CM cause you would have 5.5 meters if you mean CM.

[Stoney]

man thats what i was thinking a 450cm plant thats 4.5m now that would give off some good buds

 

cheerz

[pipeman]

do a search on "scrog" thats what you need to do in that space. Good for yield and height control