Mr Bond's Low Humidity Buster

[Mr Bond]

Sorry m8 but I don't get it, why would you want to raise humidity? If your plants have healthy roots and are watered correctly, they'll have get all the moisture they need. The r/h will naturally rise as your plants get bigger plus you slow down the rate of transpiration with a high r/h while giving ideal conditions for mould. As soon as you hit flower, you'll be trying to get the r/h down or suffer from powdery mildew or botrytis. Also, doesn't the mist cause condensation to build up inside your ducts and cause drips?

I've had to put the young plants straight under a 600 mh and the humidity was getting as low as the 20%'s, this just isn't ideal for such young plants. I was getting sever leaf edge curl as the plants were trying their hardest to transpire as fast as they could. Yes, this isn't going to kill them as long as I keep them well watered but it's still not ideal conditions. 50-60% was what I was looking for and that's now what I have.

Obviously in flower it's the opposite way round and all the foliage transpires to give higher humidity which, as you say, is the problem that can lead to mould and mildew and therefore this system wouldn't be needed. Low RH in flower also seems to give me better trich development so that's another reason to keep my RH low.

This set up is basically just to get RH up from the floor to a more reasonable level through the early days of veg, it's for the perfectionist who doesn't like to see 20% on their hygrometer, after all we don't really see such low humidity levels even on a baking summers day and if we did it would be ideal sun burn conditions which neither us nor the plants are going to like.

I should say that I can see a massive difference in the leaves with a higher humidity. Instead of them being as thin as a rizla during low humidity the are now plump and visibly full of water which in general looks better and makes for a healthy more productive plant.

Yes you do get condensation drips in the ducting but I just put a tray underneath it and the heat then evaporates any water that drips into the tray.

Edited February 6, 2013 by Mr Bond

[MED]

i did something similar a while ago but had my ducting dipping down then up. it filled up with water. quite a lot of water!

BE CAREFULL!

[Saddam]

non sequitur I put some barely rooted cuts straight under a 600w halide and they didn't bat an eyelid at 20% r/h, if your leaves are curling then the lights too close imho. Just seems dangerous having buckets and trays of water in your grow that don't really need to be there. Remember, Cannabis evolved in an arrid climate not a tropical rain forest and it developed trichomes to protect the seed against drought and uv so low humidity during veg shouldn't bother it in the slightest. Keep it simple m8.

Eta- I thought low r/h just makes the plant open it's stomata Mogggy so it can transpire more and uptake more fluids via osmosis? Don't think it slows growth, thought it sped things up but I may be wrong.

Edited February 6, 2013 by Saddam

[MED]

Eta- I thought low r/h just makes the plant open it's stomata Mogggy so it can transpire more and uptake more fluids via osmosis? Don't think it slows growth, thought it sped things up but I may be wrong.

i always knew it to be the other way around. too dry and the stomata close to stop themselves drying up.

[Saddam]

I think they only close up if there's no water left in the root zone.

eta- chop & paste (sorry) ..

Relative humidity – Relative humidity (RH) is the amount of water vapor in the air compared to the amount of water vapor that air could hold at a given temperature. A hydrated leaf would have a RH near 100%, just as the atmosphere on a rainy day would have. Any reduction in water in the atmosphere creates a gradient for water to move from the leaf to the atmosphere. The lower the RH, the less moist the atmosphere and thus, the greater the driving force for transpiration. When RH is high, the atmosphere contains more moisture, reducing the driving force for transpiration.

Soil water – The source of water for transpiration out of the plant comes from the soil. Plants with adequate soil moisture will normally transpire at high rates because the soil provides the water to move through the plant. Plants cannot continue to transpire without wilting if the soil is very dry because the water in the xylem that moves out through the leaves is not being replaced by the soil water. This condition causes the leaf to lose turgor or firmness, and the stomata to close. If this loss of turgor continues throughout the plant, the plant will wilt.

Edited February 6, 2013 by Saddam

[MED]

I think they only close up if there's no water left in the root zone.

No and yes. the do close up to maintain water when the plant is in drought. but they also close for many other reasons. so not only in drought.

Plants just don't like losing moisture to air. Stomata work at their complex jobs best around 70% - 80% RH when they are losing very little water to the air. maximizing the amount of Co2 they can breath in.

[Saddam]

Doesn't a higher transpiration rate increase the plants metabolism? Would've thought that even if the stoma weren't fully opened, they'd still fix the same amount of Co2 relative to the transpiration rate? Got me thinking now Med.

[MED]

Doesn't a higher transpiration rate increase the plants metabolism? Would've thought that even if the stoma weren't fully opened, they'd still fix the same amount of Co2 relative to the transpiration rate? Got me thinking now Med.

you logic is intuitive but the plants metabolism is not directly linked to transpiration. at the point when it transpires the least, it is growing the fastest. all other factors optimal and during lights on of course.

it gets all the water it needs from the roots for making new plant, not to transpire.

That is my take on it anyways

edit.. Co2 levels are directly linked to metabolism

Edited February 6, 2013 by MED

[Saddam]

Thanks m8, I feel more enlightened. Maybe I shouldn't be making my plants sweat so much during early veg then? By the time they're 2 foot tall, the r/h is about 60% but I've never tried to raise humidity early on. They're on 40% now (day 27) of flower but growing tiny plants atm, cuts got 5 days veg. Thanks for information.

Edited February 6, 2013 by Saddam

[MED]

I never worried to much about humidity in flower. its always been low. In veg it makes a big difference to the overall health and size i think.

I use a fogger just like Mr Bond uses and they are pretty cheap too

[miss gentle bud]

great idea mr bond.thats sorted my r h probs right out as you said its for people with low humidity probs,good job indead.

[smokeingdog]

Cracking little thing those foggers,the RH was at a SILLY 20% put a mini fogger in the tent an it is now at 65-70%,me m8 was a bit worried at 1st incase the humid air cracked his bulb,but that has not happened at all every thing as enviroment goes is PERFECT he could'nt ask for better tent weather,that is a good idea of urs mr bond it saves filling ur water tank up all the time,gonna try that out when i go me m8s later,he's the 1 doing the grow

[Chester Copperpot]

Just what I'm looking for. Top work Mr bond never heard of a fogger until today and this is what I need to do I think. What fogger works best with this system? Where can I get one and how much? Also are they expensive to run (wattage)?

Cheers

[smokeingdog]

Tried it many times and it's never done anything for me. In the room, near the intake, using as a wick and having it dangling in water and it's never helped raise the humidity in my

1.5 x 1.5 tent more than 5% and with the constant airflow it just dries the towel out in a couple of hours. If a damp towel works for you then good stuff mate but this idea is for folks like myself who suffer from super low humidity and where a damp cloth just doesn't do the trick.

my m8 was getting low RH til he got him self a mini fogger an now the plants are thriving in the high RHl it around 65-70% but it was at a SILLY 20% an the plants started to suffer a bit,they looked overwaterd/nuted but i knew they were'nt so he got a mini fogger for £20 from maplin a BANG 2 days later the plants are hugging the light hands high in the air welcomeing the light in with open leaves,so yer MR BONDS idea works brilliant,my m8 still gotta put his float an pot together yet,an he has it in the tent with the plants an a 400w hps an theres been no problems yet

Edited April 5, 2013 by smokeingdog

[Chester Copperpot]

Thanks Mr bond. Sorted my humidity I was getting around 15% humidity, with this little contraption it's now up to a steady 30% and they're looking a lot better for it, reckon I can flip them now in a week's time now.

Just a thought: I don't mist my plants but for those that do would it be an idea to have the fogger in some solution made up of whatever they use for misting? maybe it would cut the need down for misting and do it automatically

Edited April 9, 2013 by greatwhiteshark