Help help help temperature please

Help please ppl ...Right my friend knows he's stuff just from he's previous he pulls down good numbers etc fact... It's now gt cold tht when my lights go off my temp goes down to 45 he is saying this is nt a great problem we r 5 week into flowering surely this is a massive problem thing is he has a proven track record and I dnt but I'm sure this effects the yield ???

45 degrees will stop phosphorus and other nutrients from metabolizing. If the leaves and bud start turning purple, that's your sign. Some strains can stand that cold but not most. Perfection is keeping the temps the same with lights on or off.

Gotta agree, temps at 45 is way too cold and it will def effect your yield, as said, try to maintain your temps, I strive for no less than 65 deg.

You need to have 75 daytime, 60 nighttime. 45 is way too cold.

55 is the lowest you want to go 45 is way too low, get a plugin radiant heater long with a plugin thermostat control should total 150$

IMO- When the dark cycle temps get colder you grow some of your best buds. Denser, more flavorful, more colorful with purples.
During the light cycle temps still get up into the 70's.
The thing you have to watch is the temp of the soil. When the soil gets cold you get into slowed growth, and as mentioned you can lock out diff. nutrients.
It takes a while to cool off your soil. There a lot of mass there to keep heat.
Marijuana can take some cold temps. It's the duration of the cold that kills them.

IMO- I think your doing good with the conditions you have going on.
Keep in mind these plants originally grow up on the side of a mountain.

"I'm only talking about the Flower Cycle"

I was having the same problems, dropped below 60* overnight and winter just started. Switched my light to stay on overnight because the lights raise the room temps. That was this morning. Going to check the temp tomorrow morning to see what the room temp is running overnight.

55 is probably the lowest you want to go without affecting your yield, other than maybe the last week or two, if you've grown that strain outdoor in your climate it would do Ok. I grow in a cold area and I'm heating through lights off period to keep it 60'sh +-2 during lights out right now. I put a booster vent with a fan in it, made a panel to fit it into and tied into the duct work from the house, cheap and keeps the temps. If you don't have that option throw a space heater on a timer like Dirty Jerz mentioned.