temps

hi guys i'm using a 400watt mh for veg running 18/6 but for the last 3weeks or so growth
has stopped ive checked my temps and im just hitting 62 lights on. but im worried now
that with the six hours darkness it will affect my growth. so ive decided to keep light on 24hrs
till temps approve and growth inproves. but will my planets recover or are they shoot. any advice
i would be very graful cheers guys

maybe add a little heater, cold temps cause nute lockout

brayo - I think you are right to be concerned about temps. Photosynthesis is extremely temperature dependent and at 62 degree it just creeps along. In the plant I know best, the grape vine, you get a tripling of photosythesis in a fairly linear graph from 60 degrees to 90 degrees. I would imagine cannabis is not much different. I think you are right to leave on the light because at 62 with lights on, who knows what the drop is with lights off. I have been dealing with similar temp issues and found that double layering my grow tent covering (black/white poly plus mylar layer) gave me another 5 degrees. Adding a 200 watt small space heater on a quality thermostat gave me another five. Closing off venting and turning off one of the two fans at lights off gave me another five. Right now my garage is 38 degrees, my 84 cu ft tent is 77 degrees, wamed by two blackstar leds and one 400 watt hps dimmed 50% (power supply in tent). Lights off temps drop to mid 50's. Not ideal, but I have a nice crop about two weeks from chop. One thing, if you go the heater route watch your humidity and be sure the heater output is well diffused. I am running 30% RH right now, and the girls don't like it one bit.

They will recover. You want to shoot for 78F which is optimum. The Temps when the lights are off doesn't matter that much as long as they remain comfortably above freezing.

thanks guys for your replys i will check temps inabit to c if i have had a increase in temp
due to running 24hrs fingers crossed my babies will inprove.

One quibble about not worrying about dark temps. Plants don't stop working when the sun goes down. They continue to respire and produce the building blocks needed for growth. The warmer your dark temps the more dark respiration, and within limits, the more a plant may put photosynthetic sugars into plant growth and maintenance. I don't think cold dark periods (40-50) are helpful, particularly in the veg state. They will slow down the plant in dark and delay resumption of activity in light. I would try to keep the thermoperiod, that is the daily temperature swing, within 10 to 15 degrees during veg for sure. Personally, I would sure like to know the effect of temperature, both day and night, on the accumulations of resins. My sense is that my 50 degree nights have not been good for resin production, and my flowering is well behind the times suggested for my clones.