Flowering advice please...

OK, got a few questions for the next stage of my grow. Feel free to just answer the ones you are knowledgeable in.

I am growing two MK-Ultra's and Two Sour Diesels in soil for personal medicinal use in a space that's roughly 18" by 24" but with 5 feet of vertical space. Will be using only 200 watts of CFL for flowering (~12000 usable lumens)
Plants look kind of like a SOG since I have been doing LST from early on. I'd say I have about 15-20 grow tips that are all about 8" tall.


1. At what height do you recommend forcing flowering considering that I'm not willing to increase the light and so don't want 4 foot tall plants if my light can't reach down far enough anyway ?

2. Since one strain is mostly sativa and the other indica should I expect massive difference in vertical growth during flowering? How much?

3. It's getting cold in my grow room, already close to 50 degrees at night. What's your best tip for heating a small grow like this?

4. How much do the cold temps affect bud size/growth?

Thanks

Extremely cold temperatures can cause purple stems. Running your light should keep it warm. Run your lights at night when it's cold. Hopefully the day temps are better. I usually assume that my plants will triple in size. So, I start flowering at 7' or 8' in my garden and sometimes I still end up with plants almost 3' tall.

not SOG but SCROG, SOG you generally want 1 short good stem not multiple

on forced flowering most plants will generally double in size, sativas alittle more, so if you have a 5' space subtract light and pot hight(aprox. 3-3.5' grow space)i would try to flower at 1-1.5'. but since lst you could go longer veg and height of plant can be bigger

to heat up the room either add alittle electric heater or if it were me i would add another light to raise temps

what is your intake system and exhaust system like?

and cold temps affecting bud, it depends on strain as to how it does with weather, ask seed bank condition plants like, as they have best knowledge of plants you have

i agree with texas grass.

i'd flower now or sometime during the next week (after a lil flush maybe)

putting the lights on at night is a good idea to keep the temps up. i have a sealed room which stays at 17C when all equipment is off, but adequate in and out fans with a digital thermostat keep things at 25C during the day.

Good luck!!

Thanks guys,
As far as the intake/exhaust I really don't have one because the whole front of my grow has been open. I have just been sliding a large piece of styrofoam in front of it for reflective purposes. But now that I will be flowering I will need to seal for light of course so it gets a little tricky. I have had a computer fan hanging in there blowing on the plants continuously and since the top has been open they've gotten plenty of fresh air.

Not sure how I will cover the front which is actually more like 6 feet tall by 18" wide. Any ideas? A tarp with hooks ? Velcro?

Also, if I leave a hole at the top of my grow and have one at the bottom too will that be enough to draw new air by letting the heat rise and pull new air in from bottom? I would still leave the fan in there to move the air around of course, but if I SUCK air in then it will get very cold in there very quickly 'cuz the space is so small.
I also thought about sucking the air out from the bottom of the grow and in from the top. Figured maybe this would pull the warm air from the lights down to warm the plants and the soil?
The space is too small for an actual heater and if I have to heat my whole shed then it becomes REALLY expensive.

So in summary, I figured I will line the grow with reflective insulation material, and then try to just let the heat draw new air from bottom and out the top... or the reversed fan option I mentioned above... not sure which would keep it warmer?

Lastly, I thought about wrapping my pots in like a 20 or 30 watt propagation heating mat as I hear that if I keep the roots warmer then the plants can handle more cold.

Sorry to be so long winded.... any thoughts from you guys are really appreciated.