Is worth continuing with LEDs + low temperature?

[Star Dog]

I've read numerous times that the canopy temperature with led needs to be 27/28 due to infrared, the reality is i'm never going to be able to reach that figure anytime soon.

Just now it's 23c at the canopy 20/21 ambient, it's growing fine I've no complaints but I've that nagging doubt about the temps for flowering.

Should I persevere with led or swap it out for the balmy temps of hid

I'm not to fussy about minor differences in yield but I don't want to be wasting my time if the outcome is predictable?

 

[Moflow]

I've read numerous times that the canopy temperature with led needs to be 27/28 due to infrared, the reality is i'm never going to be able to reach that figure anytime soon.

There's 'Optimum Temps' for growing with leds or other lighting but cannabis will grow in a wide range of temperatures.
I grow in cold temperatures like you with leds. I like the challenge.
In the warmer months my main flowering area is around 16°C lights off, slowly rising to a max of ~ 28°C when lights come on.
In another insulated tent area for vegging my temps are ~ 22°C now, I use a 12v pc fan on a fan speed controller for min extraction and the carbon filter and fan just recirculates air in the tent.
Another area, in an unisulated attic is vegging at around 14 - 16°C this weather.
As for the winter, as you can imagine, it gets really cold lol but the plants still grow.
Ì use heat mats on timers in the cooler months as I've found that keeping the medium warm is very important.
I've measured temps of 7 - 8°C in mid winter lights out.
Ìn my experience the cooler temps in winter add an extra week or two to flowering time but no difference in quality.
Maybe you could use an HID for the winter period and leds for summer grows.

 

[bk78]

In winter it’s impossible for me to get to the “suggested” temps. So I don’t.

Max I can get to is like 24 Celsius, so I adjust my humidity to hit vpd for whatever temps I can reach

 

[supchaka]

In winter it’s impossible for me to get to the “suggested” temps. So I don’t.

Max I can get to is like 24 Celsius, so I adjust my humidity to hit vpd for whatever temps I can reach

VPD with LED’s isn’t the same as HPS. 1.5-1.7 works amazing for me.

 

[bk78]

VPD with LED’s isn’t the same as HPS. 1.5-1.7 works amazing for me.

Well my VPD is the same 1.2

I must be doing it all wrong I guess

 

[supchaka]

Well my VPD is the same 1.2

I must be doing it all wrong I guess

If you’re ok at 1.2 you aren’t pushing them very hard.

 

[supchaka]

Vegging at 1.5-1.7 works great too.

 

[Tvanmunhen]

Silly question from a noob here but doesn't the strain also play a slight role on choosing your temps and Rh. For example the breader suggest 68 to 80f and 40 Rh for Skywalker OG. PM and mold issues are a concern.

 

[rkymtnman]

I've read numerous times that the canopy temperature with led needs to be 27/28 due to infrared, the reality is i'm never going to be able to reach that figure anytime soon.

Just now it's 23c at the canopy 20/21 ambient, it's growing fine I've no complaints but I've that nagging doubt about the temps for flowering.

Should I persevere with led or swap it out for the balmy temps of hid

I'm not to fussy about minor differences in yield but I don't want to be wasting my time if the outcome is predictable?

just purely anecdotal, but foxtailing is almost non-existent since i dropped my temps to high 70'sF instead of the mid 80sF that people recommend for led b/c of lack of IR

 

[bk78]

Vegging at 1.5-1.7 works great too.
View attachment 4904595

That VPD must cause the yellowing of your leaves I guess hey? :shrug:

 

[Star Dog]

Maybe you could use an HID for the winter period and leds for summer grows.

That is my very plan, it was starting to get temps nearer 8/10c during the day so I decided it was time to get the led back out, within a week it was back to frost and snow, its a bit late this year but there's better conditions forecast for next week.

 

[rkymtnman]

That is my very plan, it was starting to get temps nearer 8/10c during the day so I decided it was time to get the led back out, within a week it was back to frost and snow, its a bit late this year but there's better conditions forecast for next week.

just a thought but how much heat would adding like a 100 watt incandescent to your room? you think that plus the leds would be enough?

i started our tomatoes outside and got caught by 3 nights below freezing. i hung a 250 w infra red (like the bulb in a bathroom vent) over them and they survived. (knocks on wood)

 

[supchaka]

That VPD must cause the yellowing of your leaves I guess hey? :shrug:

Pushing 1000+ ppfd before the 4th week of flower, kinda underestimated how much they’d be eating. Still getting things dialed in.

 

[Star Dog]

just a thought but how much heat would adding like a 100 watt incandescent to your room? you think that plus the leds would be enough?

i started our tomatoes outside and got caught by 3 nights below freezing. i hung a 250 w infra red (like the bulb in a bathroom vent) over them and they survived. (knocks on wood)

I put a 150w tube heater in today its not made a huge difference but its a 2.2.5c increase and it all counts.

It seems odd to use a led and then use a heater when a 250w hid works but I'm willing to for the learning curve and it's not exactly big wattage either lol.

 

[PJ Diaz]

I put a 315cmh next to my LEDs during the cold of winter. It's better than a heater, because it puts out PAR photons as a byproduct in addition to radiant IR heat.

 

[bk78]

Pushing 1000+ ppfd before the 4th week of flower, kinda underestimated how much they’d be eating. Still getting things dialed in.

But you just showed vegging pics tho?

 

[supchaka]

But you just showed vegging pics tho?

Oh come on they’re not that yellow. They’re old moms anyway, they’ll be thrown out soon. They’re in 2 gal pots and only had water the last two weeks. I keep them around while I’m cloning in case some catastrophe fucks up my cuts. Next round is rooted and in the trays so I’m safe to chuck the moms.

 

[supchaka]

If u want to tease about yellow plants use these. Only day 45. They started fading at 4 weeks which is when I started adding back a little nitrogen. I have a pretty good idea what I need to do for next round. This entire grow has had a vpd from 1.5-1.7 and Co2 only 500-700ppm. I can’t hit the temps necessary to push high co2 so I don’t try.

 

[1212ham]

I've that nagging doubt about the temps for flowering.

Will you be turning up the lights for flower? What's your room temp?

Insulation and minimizing air flow and can really raise temps. Like Moflow, I use a 12v pc fan with speed controller but it's also on a humidity controller.

I made a 50x90 cabinet from 25mm foam insulation board. It got too hot as spring arrived so I moved to my 50x90 tent and had to add a little heat, an old waterbed mat running on a dimmer.
Now it's time to put in the window shaker.

I sure would be nice to have little hid lights with decent efficiency.

 

[1212ham]

just a thought but how much heat would adding like a 100 watt incandescent to your room? you think that plus the leds would be enough?

i started our tomatoes outside and got caught by 3 nights below freezing. i hung a 250 w infra red (like the bulb in a bathroom vent) over them and they survived. (knocks on wood)

FWIW, I asked about incandescent for seedlings and learned they have some undesirables in the spectrum, no idea about using a little for veg or flower though.