Pot Size and Room Humidity

With the Subcool Super Soil method and 7 gallon pots from the start, I get a lot of humidity in my small grow room. The pots also take a very long time to dry out when the plants are small. This can contribute to peat flys, and symptoms of overwatering.

Without getting a dehumidifier, is there another way to control the humidity and moisture holding capacity of the soil when using large pots from the start?

Comacus said:

With the Subcool Super Soil method and 7 gallon pots from the start, I get a lot of humidity in my small grow room. The pots also take a very long time to dry out when the plants are small. This can contribute to peat flys, and symptoms of overwatering.

Without getting a dehumidifier, is there another way to control the humidity and moisture holding capacity of the soil when using large pots from the start?

Click to expand...

Grow only one plant and veg it super long. Otherwise get a dehumidifier. What is the RH in the grow room and do you exhaust outside or in your basement?

Right now the RH is 65%, and the ambient RH is 42%. I am venting to outside with a 4" variable speed can fan (155 max cfm I think). I am using an 8 bulb 4' T5 HO fixture.

I did turn 4 lights off recently, and the RH went up. I think that was primarily due to the fan being temp control, and it did not run at a higher speed because less heat was being generated.

I think I have seen in a few of your other posts that you do use transition pots. While Sub recommends using only one size from the start, I suspect that building up to the larger pots would also help as the plants would use more water as they matured, and went into larger pots.

Thank you for your help.


I just turned on the other set of lights to see what it comes down to in the room.

I have had bud rot once. While I have a lot of airflow from a fan, and think I have pretty good venting, the RH was probably a factor.

as long as the air is really moving a lot you shouldnt get budrot. another thing when are just transplanted in the 7gal pots you dont need to water them that much. the roots will really grow out. so for the first few waterings you dont really need to drench the whole 7gal bucket.

Keep the air moving for the flowers as said... airpots + properly aerated soil = overwatering impossible

venom21 said:

as long as the air is really moving a lot you shouldnt get budrot. another thing when are just transplanted in the 7gal pots you dont need to water them that much. the roots will really grow out. so for the first few waterings you dont really need to drench the whole 7gal bucket.

Click to expand...

I believe this is not accurate information, even with lots of airflow, with RH above 50% it is def. possible to get budrot.

You have to look at your setup, and improve it. You cannot grow buds with RH above 55%, or you shouldnt risk it...

The first thing to do when trying to grow meds is to dialled in the environment, until that's done, it's like playing the Russian roulette .



EDIT: BTW, I grow 12/12 from seed and I go from 16oz container to 7 gallons, I dont repot over and over, I believe to grow big buds you have to grow great root system before the plants start budding.

I prefer to grow plants in big pots but only after sexed... i'm not wasting 7g worth of soil on an unsexed seedling I repot twice from seed... start in 16oz/.3g, move up to 1-1.5g move up to 1.5g after 3 weeks until sexed (preflowers), then big pots for females... if clone start out in the big pot no need to repot.