Planning first grow - temperature help

E

E Mahn

Member
I am planning my first grow in a 3x3x6 tent, four 3-gallon pots, scrog, soil, LED 600W light, 200 CFM exhaust fan, probably clones (Tangie).

The tent will be in the crawl space under my house (it is a tall space with plenty of room to walk in). It is sort of semi-indoors/semi-outdoors. It is enclosed with walls but there are many vents that allow air to enter and exit to the outside. Because it it half underground, it is very well insulated - stays cool in the summer and (relatively) warm in the winter. The temperature does not fluctuate during the day nearly as much as the outdoors, but it is globally affected by the seasonal temperature outside.

I think this will be the ideal environment for the tent come next summer (perhaps 60-70 degrees). But my first grow will be early January. I live in Northern California, so the weather outside isn't that extreme, but during the winter I expect that the temperature in the crawl space will be 50-55 (maybe high 40s for low, I'm not certain).

I think the "daytime" temperature inside the tent will be fine with the lights on. But when the lights go out, with the exhaust fan on, it will drop the temperature inside the tent to match the surrounding crawl space. Especially during 12/12 flower, this will be a long time at cool temperature. I expect and accept that this will lower overall production. But my question is this - how much this temperature will affect the overall growth? I don't need to be making the highest possible production. This is only to supply my own personal need. So will it completely stunt the bud development and be not worth the investment in time and money? Or will it just be at a lower production level? If it's 75% of optimal or even 50%, then I can probably live with this. If it's less than 50%, perhaps it's not worth it.

Heating the overall crawl space is not an option. First, it's huge, and it is vented to the outdoors; I am not ready to spend gobs of $ on the electricity needed to heat it. Heating inside the tent is not really an option either. It's a small tent and it will be pretty tight in there with the 4 pots and I really don't want the headache of trying to manage the issues with a heater inside a tight enclosed space. My question is really whether this would be viable without heat.

Thanks.
 
Last edited:
Lordhooha

Lordhooha

Well-Known Member
E Mahn said:
I am planning my first grow in a 3x3x6 tent, four 3-gallon pots, scrog, soil, LED 600W light, 200 CFM exhaust fan, probably clones (Tangie).

The tent will be in the crawl space under my house (it is a tall space with plenty of room to walk in). It is sort of semi-indoors/semi-outdoors. It is enclosed with walls but there are many vents that allow air to enter and exit to the outside. Because it it half underground, it is very well insulated - stays cool in the summer and (relatively) warm in the winter. The temperature does not fluctuate during the day nearly as much as the outdoors, but it is globally affected by the seasonal temperature outside.

I think this will be the ideal environment for the tent come next summer (perhaps 60-70 degrees). But my first grow will be early January. I live in Northern California, so the weather outside isn't that extreme, but during the winter I expect that the temperature in the crawl space will be 50-55 (maybe high 40s for low, I'm not certain).

I think the "daytime" temperature inside the tent will be fine with the lights on. But when the lights go out, with the exhaust fan on, it will drop the temperature inside the tent to match the surrounding crawl space. Especially during 12/12 flower, this will be a long time at cool temperature. I expect and accept that this will lower overall production. But my question is this - how much this temperature will affect the overall growth? I don't need to be making the highest possible production. This is only to supply my own personal need. So will it completely stunt the bud development and be not worth the investment in time and money? Or will it just be at a lower production level? If it's 75% of optimal or even 50%, then I can probably live with this. If it's less than 50%, perhaps it's not worth it.

Heating the overall crawl space is not an option. First, it's huge, and it is vented to the outdoors; I am not ready to spend gobs of $ on the electricity needed to heat it. Heating inside the tent is not really an option either. It's a small tent and it will be pretty tight in there with the 4 pots and I really don't want the headache of trying to manage the issues with a heater inside a tight enclosed space. My question is really whether this would be viable without heat.

Thanks.
Click to expand...
Like crypto said run your lights at night to keep the temps right. In theory you don't want anymore temp difference of 10 degrees from lights on to lights off
 
E

E Mahn

Member
So the thing is, in terms of real world day/night, the temperature in the crawl space doesn't really change. It will be in the 50-55 degree range all day/night. But for the plants' day/night, it will change a lot. With the light on, I expect the tent to be in the 70s. But as soon as the light goes out, it will drop to 50-55. I can't keep the light on outside the 12/12 schedule during flowering.
 
moondance

moondance

Well-Known Member
Hey bud I grow in a basement in similar conditions if you get a minute check the thread in my signature, i have pics and stuff, just how i do it is all, may help may not. Peace.
 
Rudi I&I Automan

Rudi I&I Automan

Well-Known Member
get yourself a lightbulb water cooler if poss, 600 watts in such a small tent will become a problem l8r on during flowering or a carbon fume /oder scrubber/eliminater or set 2 fans in the top of the tent (it should have some openings for heat elimination, well lessening of heat in the tent. if temps are too high (best to run the set up with no plants first and take temp measurments to be sure of your growing enviroment b 4 planting. one way i do it is to place my hand under the light and if i can hold my hand there without it getting too hot, the plants should cope just fine (variaty depending)
 
Lordhooha

Lordhooha

Well-Known Member
moondance said:
Hey bud I grow in a basement in similar conditions if you get a minute check the thread in my signature, i have pics and stuff, just how i do it is all, may help may not. Peace.
Click to expand...
His problem is it a crawl space my rooms are in my basement however my basement is heated and cooled.
 
moondance

moondance

Well-Known Member
Sorry Hooha I will pay better attention, I was hella busy that day. My basement stays 81 lights on year round and 76 lights off. Good to see you!
 
moondance

moondance

Well-Known Member
OP I run my lights at night to help keep them warm during the coldest part of the day, and I block off any light from windows to keep them dark in the daytime. Temp range you want to stay within a 10-15 degree temp difference from day to night if i remember correctly, please someone correct me if I am mistaken.
 
E

E Mahn

Member
Thanks folks for your posts.

A couple clarifications:
> Running lights at night vs. day won't help a lot here. Because it is half underground, there is very little temperature difference between night and day, maybe 5 degrees. During the winter the crawl space temperature range is 50-55, night vs. day.
> The tent has (or will have, I haven't bought it yet) a carbon filter/scrubber with inline fan. Also circ fans.
> I'm not anticipating that heat will be an issue, especially not in the winter. The crawl space is pretty cool all year and LED light will run relatively cool. The inline fan (200 CFM ) has an adjustable rate control, so I can punch it up if it gets hot.

Rudi: Great idea on running the equipment solo with no plants as a test. I will do that.

So I completely realize that this isn't ideal, but I am willing to accept non-ideal. I'm just wondering if anyone has experience growing when the lights-out temperature drops to 50 degrees. I've read a little where people purposely drop temps to heighten the purple color, but I'm not clear on specifics. I haven't bought the equipment yet, so if the plants won't produce at all in this setting, then I should probably wait until summer. But I am really anxious to start and would prefer to do a winter run, albeit with lower production, as long as it produces something smokeable.
 
It's not oregano

It's not oregano

Well-Known Member
Just an idea, but what about auto's not photo's? Do them on say 22/2 with the 2 being at the warmest 2 hours of the day. That way they are not spending half the day in the cold, and will be finished quicker so your electric bill won't be much different than a longer photo grow.
People say auto's have improved over the years, and if you are not obsessed with quality/yield they might be ideal for your needs.
Not wanting to cause an auto/photo fight, just trying to give another option you may not have thought about.
P.s. E Mahn is a name that means a lot to me, but a totally different person. Nice to see it written again.
 
E

E Mahn

Member
It's not oregano said:
Just an idea, but what about auto's not photo's? Do them on say 22/2 with the 2 being at the warmest 2 hours of the day. That way they are not spending half the day in the cold, and will be finished quicker so your electric bill won't be much different than a longer photo grow.
People say auto's have improved over the years, and if you are not obsessed with quality/yield they might be ideal for your needs.
Not wanting to cause an auto/photo fight, just trying to give another option you may not have thought about.
Click to expand...
So that is a creative thought and I had not considered it. Thanks. Although I understand the general concept, I really don't know a lot about autos. My seed/cutting supplier doesn't carry any autos, but perhaps I should seek out another source.
 
slow_grow

slow_grow

Well-Known Member
Not sure why it hasn't been mentioned and maybe I'm off, but 4 3G pots in a 3x3 will be extremely cramped for the plants let alone any tending that needs to be done. 2 happy plants would more than fill a 3x3. 2 happy plants in 5G would be beast mode plus if you bumped up the pot size your watering frequency will be far less. My first run were autos in 3G pots and towards the end of veg they needed full waterings every 48 to 72 hours. Not a big deal in theory until your lugging around gallons of water down into your crawl space every few days.

Is that 600W true watts of LED? You mention punching up the inline fan to keep things cool but keep in mind you'll need to provision for extra intake as the excess negative pressure will be a detriment to the plants. If you plan to put a scrubber on it get a bigger fan, 200CFM with a scrubber will be taxed moving just 120 CFM. Better to have a slightly larger fan working less.

The temp solution can be solved with tiny space heater just for the tent. You can get a small personal heater with built in temp control for like $30 that's smaller than a shoe-box. Set it to 60° and it will only need to run periodically through the night during lights off.
 
E

E Mahn

Member
slow_grow said:
Not sure why it hasn't been mentioned and maybe I'm off, but 4 3G pots in a 3x3 will be extremely cramped for the plants let alone any tending that needs to be done. 2 happy plants would more than fill a 3x3. 2 happy plants in 5G would be beast mode plus if you bumped up the pot size your watering frequency will be far less. My first run were autos in 3G pots and towards the end of veg they needed full waterings every 48 to 72 hours. Not a big deal in theory until your lugging around gallons of water down into your crawl space every few days.
Click to expand...
I was advised elsewhere that I could go 1 pot, 2 pot or 4 pots (smaller pots as the number increases). 4-pot was based on 3-gal pots. Your input is helpful.
With regard to watering, I will be using an autopot system, so this will limit need to lug.

slow_grow said:
Is that 600W true watts of LED? You mention punching up the inline fan to keep things cool but keep in mind you'll need to provision for extra intake as the excess negative pressure will be a detriment to the plants. If you plan to put a scrubber on it get a bigger fan, 200CFM with a scrubber will be taxed moving just 120 CFM. Better to have a slightly larger fan working less.
Click to expand...
Light is 600W "equivalent." Actual watts are a little less than half that (275 IIRC).
For intake, my plan is for 2x 4" passive intake (compared to 1x 4" active exhaust). I could easily change this to 2x 6" passive intake. If I change the fan, I would go with larger intakes.
I'll think about the bigger inline fan. Again, this was the input I got elsewhere.

slow_grow said:
The temp solution can be solved with tiny space heater just for the tent. You can get a small personal heater with built in temp control for like $30 that's smaller than a shoe-box. Set it to 60° and it will only need to run periodically through the night during lights off.
Click to expand...
I'm really nervous about a traditional heater inside such a tight space. It's hard for me to see where it will fit, especially as the plants get bigger. The floor of the tent will be a watering tray used for the autopot system. I considered using a seedling mat under the watering tray and setting the temp to about 70 degrees. I'm not sure how much that will affect the ambient temp in the tent though.
 
E

E Mahn

Member
Here is the latest update:

> I am going to grow autos so I can keep the light on longer, say 22/2 (or even 24/0 if I have to)
> I will put a large seedling heat mat under the pots (this is only about 85 watts, so it will help with soil temp, but is limited)
> Change to a 600W HID light

I expect the ambient temp to be about 45deg F in the crawlspace. The inline fan carbon scrubber will be pulling in air from the crawl space.

What do you think? Will a 600W HID light keep the tent warm enough? I will eventually test this, but I can't really start the grow and test until after Jan 1 (when it is coldest).
 
purplehays1

purplehays1

Well-Known Member
E Mahn said:
I am planning my first grow in a 3x3x6 tent, four 3-gallon pots, scrog, soil, LED 600W light, 200 CFM exhaust fan, probably clones (Tangie).

The tent will be in the crawl space under my house (it is a tall space with plenty of room to walk in). It is sort of semi-indoors/semi-outdoors. It is enclosed with walls but there are many vents that allow air to enter and exit to the outside. Because it it half underground, it is very well insulated - stays cool in the summer and (relatively) warm in the winter. The temperature does not fluctuate during the day nearly as much as the outdoors, but it is globally affected by the seasonal temperature outside.

I think this will be the ideal environment for the tent come next summer (perhaps 60-70 degrees). But my first grow will be early January. I live in Northern California, so the weather outside isn't that extreme, but during the winter I expect that the temperature in the crawl space will be 50-55 (maybe high 40s for low, I'm not certain).

I think the "daytime" temperature inside the tent will be fine with the lights on. But when the lights go out, with the exhaust fan on, it will drop the temperature inside the tent to match the surrounding crawl space. Especially during 12/12 flower, this will be a long time at cool temperature. I expect and accept that this will lower overall production. But my question is this - how much this temperature will affect the overall growth? I don't need to be making the highest possible production. This is only to supply my own personal need. So will it completely stunt the bud development and be not worth the investment in time and money? Or will it just be at a lower production level? If it's 75% of optimal or even 50%, then I can probably live with this. If it's less than 50%, perhaps it's not worth it.

Heating the overall crawl space is not an option. First, it's huge, and it is vented to the outdoors; I am not ready to spend gobs of $ on the electricity needed to heat it. Heating inside the tent is not really an option either. It's a small tent and it will be pretty tight in there with the 4 pots and I really don't want the headache of trying to manage the issues with a heater inside a tight enclosed space. My question is really whether this would be viable without heat.

Thanks.
Click to expand...
You do not need to worry about cold, it is heat that will more likely be the issue for a month or two in the summer. I have friends that grow in nor-cal without AC's or heaters in garages without issue. Put ur exhaust fans on a themostat so they arent pulling in tons of cold air during the day (plants night) and u will be fine. The lights will keep the plants plenty warm when it is cold outside at night in the winter, and day time temps in nor-cal are not likely gunna freeze ur girls indoors.
 
B

BeeDabbin

New Member
E Mahn said:
I am planning my first grow in a 3x3x6 tent, four 3-gallon pots, scrog, soil, LED 600W light, 200 CFM exhaust fan, probably clones (Tangie).

The tent will be in the crawl space under my house (it is a tall space with plenty of room to walk in). It is sort of semi-indoors/semi-outdoors. It is enclosed with walls but there are many vents that allow air to enter and exit to the outside. Because it it half underground, it is very well insulated - stays cool in the summer and (relatively) warm in the winter. The temperature does not fluctuate during the day nearly as much as the outdoors, but it is globally affected by the seasonal temperature outside.

I think this will be the ideal environment for the tent come next summer (perhaps 60-70 degrees). But my first grow will be early January. I live in Northern California, so the weather outside isn't that extreme, but during the winter I expect that the temperature in the crawl space will be 50-55 (maybe high 40s for low, I'm not certain).

I think the "daytime" temperature inside the tent will be fine with the lights on. But when the lights go out, with the exhaust fan on, it will drop the temperature inside the tent to match the surrounding crawl space. Especially during 12/12 flower, this will be a long time at cool temperature. I expect and accept that this will lower overall production. But my question is this - how much this temperature will affect the overall growth? I don't need to be making the highest possible production. This is only to supply my own personal need. So will it completely stunt the bud development and be not worth the investment in time and money? Or will it just be at a lower production level? If it's 75% of optimal or even 50%, then I can probably live with this. If it's less than 50%, perhaps it's not worth it.

Heating the overall crawl space is not an option. First, it's huge, and it is vented to the outdoors; I am not ready to spend gobs of $ on the electricity needed to heat it. Heating inside the tent is not really an option either. It's a small tent and it will be pretty tight in there with the 4 pots and I really don't want the headache of trying to manage the issues with a heater inside a tight enclosed space. My question is really whether this would be viable without heat.

Thanks.
Click to expand...
Hey man I built around my tent and insulted it lol so now I just gotta figure out my humidity
 
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