Cultivation Q - humidity control

[Artificial Emotion]

Theoretically if someone were cultivating cannabis and you wished to have control over ambient humidity levels what methods would you recommend to control levels that you would recommend? Here's what info I've personally found online:

During the vegetative stage higher humidity levels are required (apparently 40-60%). To increase relative humidity (RH) levels you could use a humidifier, although these use a tremendous amount of power and expensive to run). I've read that mini foggers (see photo) which cost £15 each at Maplins in the UK. These purportedly increase levels of RH without heat. A couple should work well. Another way to increase RH is to decrease ambient temperature levels (to a minimum of about 77F IMO. You could also use a mister/spray, being careful with electrical items or place wet towels on the floor.

The only way I know to decrease RH levels is to use a dehumidifier or increase ambient temperature to a maximum of 85F, which is pushing it. Would some sort of dessicant like calcium oxide work I wonder? Ventillation also helps.

 

[Sega420]

humidifier and a dehumidifier. voila

 

[Artificial Emotion]

The humidifier uses a hell of a lot of power. If two mini foggers will be sufficient then I think they are a better solution. The lights alone cost a fortune to run.

Do these (de)humidifiers have inbuilt humidistat/hygrostats that monitor RH and control the device to maintain the RH? Do they have dials where you select the desired humidity and then just leave it? Do they turn on and off like a thermostat-controlled heater? Do they allow you to have accurate control over RH levels?

 

[Chainer]

heartfelt humidity beads.... Billons of em!

Ever walk into a cigar shop or cigar section? Really easy and cheap way to mantain humidity up to 80% for large rooms depending on setup.

I personally use a very large vinotemp I converted.

 

[Artificial Emotion]

Well I just got a couple of mini foggers in the post (my flat is quite dry) and they work a treat - this is a much better option IMO. They're very cheap to buy and run, so thumbs up from me!

One more thing - they look very cool.

 

[thujone]

if you're going to keep humidity constantly over 50% you should have adequate ventilation to keep mould from growing. and by adequate i mean you should be able to feel a breeze between the nodes

 

[Blowmonkey]

Saw you tried to pm me, cleared some space.

Fwiw, it's actually a good thing your apartment is on the dry side, at least, if that's the place you're intending to grow in. As long as it's not a huge set-up involving CO2 equipment etc, high humidity levels during vegging isn't necessarily needed. It's a pro ofcourse, but you can easily do without. Only clones need to be kept at a high rh, bigger (cloned) plants don't really need it, neither do seedlings.

Clones can be kept in propogators to increase humidity, even then it's recommended only to keep them at a steady rh of say 60-80 in the first few days, after that you gradually decrease rh by lifting the lid for longer periods of time, untill they root. A fogger can come in pretty handy for these kind of transition periods, I don't use em, I don't really know how they work, I guess you could hook it up to a timer to increase rh for short periods of time, during which time you switch off the outtake or the circulating fans or something.

 

[Artificial Emotion]

Yes I do agree, humidity isn't ad big of an issue as a lot of people think. I do however think increasing the humidity levels in my case from 40% to 60% will have some benefit m, even if marginal. I will use a dehumidifier during flowering to try and reduce the humidity to 30% to prevent bud rot. When using a single mini fogger it can be left on constantly and doesn't require the ventilation fans to be turned off.

When I can afford it I will buy CO2 equipment (a regulator, tank etc.). This is probably one of the best pieces of equipment you can buy. A 200% increase in growth rate is common, which is welcome since I'm growing organically in soil which can be a bit slower than hydroponic grows. In the meantime I've got a demijohn bottle fitted with a twin bubble airlock that has champagne yeast, yeast nutrient (diammoniun phosphate and ammonium sulphate - this increases the rate of fermentation and therefore the evolution of CO2), glucose and water which provides a form of crude CO2 enrichment.

BTW, I also just got a really cool fan controller (called the SMSCOM fan speed controller and only cost £99). It uses an external temperature probe to measure the temp and adjusts the intake and exhaust speeds accordingly and has good control over histeresus. When I get a bigger fan (6", 725m^3/hour), I will use this as the exhaust and my current 4" fan as the intake instead of a passive intake.