my grow room is 2m high when should i start to flower

my room is 2 m high my plants are 3 wks are between 10 and 20" when should i start 12/12 and whats the range i should keep 600w light , whats highest temp it should go and be safe ? m

depends. strains can double to triple in size while in flower. i really wouldnt wait too long, 1 600w isnt going to give much light penetration down low to big ass plants.

open air 600w should be at least a foot away from the plants. hold your hand under the light at where the plant tops are, if it burns you, move it up.

with co2 80-85, without 72-78 is safe.

vilify said:

depends. strains can double to triple in size while in flower. i really wouldnt wait too long, 1 600w isnt going to give much light penetration down low to big ass plants.

open air 600w should be at least a foot away from the plants. hold your hand under the light at where the plant tops are, if it burns you, move it up.

with co2 80-85, without 72-78 is safe.

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so do you recomend i put in another light ? iam already having prob keeping my temp dwn

Looks like you've got plenty of light to me. No need to add another. I would put your plants to flower when they are 20-24". Small plants will triple in size but bigger plants tend to only double or a little more. If anything, later in flower when they start filling out you can add a few CFL lights lower in the canopy.

Seems like they are ready now but your choice...with that 600 watt light you may end up having to clip the lower branches due to light deprivation ...happy trails and good luck to you...

If your tent is 6 feet high, you have about 3 feet of usable grow space, from the surface of the medium to the bottom of the HPS. If the HPS isn't in a cool tube, you probably won't be able to get it less than 10"-12" from the plant tops. So you have two issues:

1. You're already getting close to running out of headspace, once your plants go through their growth spurt when you go to 12/12, and

2. Heat. You will probably need better ventilation, and/or more airflow over your HPS. My last grow was a major PITA because I didn't plan for headspace, and I had to supercrop and LST every day toward the end of bloom, and I'm sure it hurt my yield. You really don't want that problem.

So, yeah, you probably don't want to wait too much longer to go to 12/12, and you're almost certainly going to have to improve ventilation to maintain temperature.

Just my $.02 worth. Peace!

12 to 24 inches from plants for light. 24 inches+20 inches(size of plants) personally i start flowering 20 to 25 inches because they will double during flower. that means u got about 35 inches from the bottom of the pot. i would start flowering now and maybe throw some 2700 cfls at the bottom for wider spread bud production

whats the max temp with co2 going in

vilify said:

depends. strains can double to triple in size while in flower. i really wouldnt wait too long, 1 600w isnt going to give much light penetration down low to big ass plants.

open air 600w should be at least a foot away from the plants. hold your hand under the light at where the plant tops are, if it burns you, move it up.

with co2 80-85, without 72-78 is safe.

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Grasshopper your answers are here.

culby84 said:

whats the max temp with co2 going in

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With Co2 you wanna try and keep it 88 or under if you can. Some guys go 90.