Cold temps in winter! How do i keep 18c roots?

[riz]

Hi Guys, I've got some nute lockout going and i believe it might be down to cold temps at lights out. I am growing in my loft and it gets cold.

Research has led me to believe that cannabis only slows down once temps drop below 10c or 50f, (i'm gonna use C from now on) and growth stops at 5c.

So i have been watching the temps in the loft and they have been hitting around that, only once went to 8c.

Must take ages from when lights are on for the roots to heat up to reach 18c.

I have some weird nute deficiencies going, different ones on different plants, same strain and pheno, that should all have been covered in the feeding schedule, PH sitting at decent levels. ( I don't normally have to check PH with "plant magic plus" compost and nutes ).

Do you guys think the my temps could be the problem and what do you think the solution is?

I've already drilled one hole in a ceiling to vent the hot air from the tent in the loft and mrs riz doesnt really want me drilling another so i've no way to intake warmer air.

So a new round of research and apparently cannabis roots are happiest at 18c, if the roots are at that temp then what temp above ground doesn't matter as long as it don't go below freezing.

I wanna aim for a root temp of about 18c but don't know the best way to do it, i have a 120x120x180 tent, 3 trays, 120x40cm and heat pads don't come anywhere near that size or in any combo that would fit. i don't fancy running small ones under each pot. i would need 6 greenhouse tube heaters and they would have to sit between the pots otherwise the heat is going to be extracted almost instantly and only the close ones will benefit.

I could switch the direction of airflow so i am intaking from room temp bedroom and extracting to loft, but my mr paranoia weed destroya won't let me as the police do have a heat seeking chopper that goes on searches of the woods behind my house at night regularly. I could put a 3kw oil radiator heater just outside the intake but doubt it would be effective plus being a 3kw it is unable to go on a standard timer, needs a contacter, i am not in when my lights go off and on usually so manual switching wont work.


how do you do it? any idea's?

 

[Joe Dirt]

I just experienced something similar. Yes, low temps can really mess w/pH, which messes with everything. In may case, the pH dropped and locked out most of the nutes (the room temps never dropped below 15c). So, I had to do all the things one has to do to fix nute lock... flush.... 2gals water per gallon of soil mix. Then I had to check the pH of my soil mix again and amend it to bring the pH back in line... a pain in the butt, but that's pretty much what it takes to get things back on the right track. So, there is more to be concerned with than what temps roots will live or die from.

I could switch the direction of airflow so i am intaking from room temp bedroom and extracting to loft

Just from the things you wrote, this may actually be your best option but, I don't know your situation. Something will have to be done to regulate your temps or you're going to have a lot of difficulty.

This is what I did. I got a thermostat that controls my exhaust fan. It turns the fan completely off when temps drop below 15c. I placed a space heater (without blower) a few feet from the tent and used the thermostat to regulate operation of the heater. This took some experimenting to get just right but I don't have those problems anymore.

 

[riz]

Thanks for the input mate

My ph is right though. runoff comes out at 6.5 in soil. it's when measuring ec that you need to take water temp into consideration and most ec meters have a built in thermometer to auto adjust. The loft is insulated between the loft and the house but un-insulated between loftspace and outside. A space heater would have little effect on the loft temps unless blowing directly into the tent, even then with the extraction its going straight out. even if it could make a difference, i don't want to have a hotter loft than everyone else in my street, last year when it snowed i had to do a midnight run with salted water in water balloons and go round de-icing my neighbours roofs works a treat btw.

I thought about a temp controller but it would mean fan off for whole of lights out and the house stinks after 10 mins of fan being off, mrs riz can tell before me.

I'm gonna keep on at mrs riz to allow me one more intake hole in the ceiling through to the loft from one of the bedrooms.

 

[Muddy]

Two of these would probably do the trick, 48" long by 20" wide. http://www.greenhousemegastore.com/...ng-equipment?gclid=CLKVuL7io60CFQ9Y7AodB1z8lA

I've got a similar situation with my outdoor grow box. I intake my air directly from outdoors so I'm bringing in cold air all the time. I'm using LEDs so don't have excess heat to get rid of, I need to keep it in, yet still turn over the air in the box. I've got a small space heater in there and a variable speed controller on my fan. I've got my fan running on the lowest speed so it's not drawing all the hot air out so fast.

 

[roadsidevendor1]

lights are a great generator of heat,
can you add a few twisty cfl bulbs at
soil level,
a little warmer down there and more
light to grow on.
also a small fan placed at the top of
your tent,aimed downwards,to push
warmed air back down.

 

[riz]

muddy those mats are the right length and could be folded slightly to fit in the trays, i would need 3 tho so 180 bucks thats about 120 quid before shipping. Bit too pricey nice find though i hadn't found any 4 footers. RSV the lights on is the way i was gonna go for time being so i left the lights on and it's been a sunny day here today, high in tent today was 28c

i think setting up heaters, controllers, temp sensors and timers to keep a better temp range is gonna be way too much work and expense and it will all have to be switched over to cooling come spring so i am gonna keep on at mrs riz to allow me one more hole in a ceiling to allow a more constant room temp airflow. gonna cost 5 quid for a vent grill and a tenner for a bucket of paint to repaint ceiling to blend the vent in.

 

[Muddy]

You might be able to find them cheaper. I had seen them before so knew they were out there. That was just the first one I can across, didn't check for who had the cheapest.

If your floor is cold and the plants are sitting directly on the floor, you might want to raise them up a bit. That will help to circulate the warm air around them and keep the pots a little warmer.

 

[Red eyed c]

Also you could try wrap some rock wool or loft insulation around yr pots that should help keep them a little warmer,my next door neighbour has done this in his greenhouse and his tomatoes are still going strong in December

 

[riz]

the floor has insulation between the ceiling below and the floor of the loft. heh heh if i wrap the pots they will no longer be airpots, but thats a good idea. I do have a load of bubble wrap i might be able to cut to size.

 

[Muddy]

This has gotten me to thinking, it might not be bad ideal to get a thermometer with a long probe and check mine.