New Grower lighting and gettin the right temp

[sleepy]

• 
  
  NEED MORE HELP. ive decided to go with a 400w dimmable ballast so ive got more control.
  got 4 cuttings of cheese in my tent. ive got my light on 250w and its about just over a foot above plant tops. ive got the thermometer on the floor and I had an over night low temp of 18.4 C. is this too cold?
  should I lower the lamp or will this harm the plants?
  where is the best place to put the thermometer for the best reading?
  whats the ideal temp for plants at this stage??
  
  this is my first grow so need lots of advise
  
  
  you can see my thermometer in the middle is this ok here. got a fan on the left corner blowing away which is creating a slight breeze around the tent. ive read this will make the plants stronger.
  
  all advise is welcome cheers.....sleepy
  ​
  
  

 

[Muddy]

Your thermometer should be at the top of the plant canopy. Under HPS lighting your ideal temperature is 80 degrees. 18.4 c, or about 65 f, is a bit too cool. You may need a small space heater to keep the temps up during lights out. Lowering your light much more may burn the upper leaves on your plants. A good rule of thumb is to hold your hand, palm down, at the top of the canopy for 30-60 seconds. If it feels too warm on the back of your hand, it's too warm for the plants.

 

[sleepy]

that was 18.4c with the lights on over night. my tents in my shed and its a bit nippy at the mo. maybe raise the plants off the floor to a warmer part of the tent and raise the light too . ill try moving my thermometer to the canopy to get a better reading and go from there.
thanks for the advise....

sleepy

 

[happily]

could throw a couple cfls in to boost the heat as well but you'll probably need a heater when you start a dark period

 

[Muddy]

Yes, raising the plants up will help. Are you running an extraction fan to pull air out of the shed?

that was 18.4c with the lights on over night. my tents in my shed and its a bit nippy at the mo. maybe raise the plants off the floor to a warmer part of the tent and raise the light too . ill try moving my thermometer to the canopy to get a better reading and go from there.
thanks for the advise....

sleepy

 

[sleepy]

managed to raise them about a foot but only had one bucket. gonna check the temps in bout 20 mins. ive also moved the thermometer up. gonna get something to go a bit higher tomorrow. haven't put the extraction on cos it was drawing cold air through the vent and the temp really did drop.

 

[newbud]

get your self a
Tube Heater

:thumbs:

 

[Duggy]

Tube heater or heat mat are ideal... Only 50-60w generally..

 

[greengherbs]

Agree tube heaters are great mate!

 

[blinky]

I'm growing in a garage under 400w HPS and need three tube heaters, two are on constant the other comes on during lights out. this keeps my temps just about right on an 18/6 light schedule. it depends very much on the ambient temps where you are. I tried a oil filled rad but it was a pain keeping a happy medium. the tubes work well and don't take up to much space, easy to add or pull them using timers. hope that helps.