Growing questions

A question from a fellow grower:

just need some advise on his current 1st grow attempt.

Some info:

Closet size is, (1meter wide, 600mm deep and 1.7meter tall). Grow medium is Peat moss mixed with vermiculite and perlite. Nutrients are Bio-grow 1ml per liter + Bio-bloom 2.5ml per liter at the start of week-5 of bloom.

Plants are 2 UK cheese from clone and 1 Jack Harer from seed, in 11 liter pots and under scrog with a 250w HPS. 1 small fan under scrog pointing up toward light and 1 exhuast fan 100mm diameter with rating of 2.12m squared per minute. (roughly 2 times air exchange per minute.) Light is about 30cm from tops.

Plants are in 5th week flower and buds look like they are just starting to fill out on the cheese but still stretching slightly on the Jack.

Its winter here so temps during daytime (lights off) is roughly 10-15 degrees celcius with up to 90% RH (inside closet and out in room) and night time, (lights on) 22 - 24 degrees celcius with around 47% RH.

Humidity during lights off is extremely high even going over 90% but swim added 2 passive de-humidifying tubs bought from a hardware store that uses calcium chloride to extract moisture. These work a bit but RH stills get up 80% on cold rainy days when lights are out and temps drop to around 10 degrees Celsius. All fans are off during light off period because swim doesn’t want the cold air from the room to be brought into the closet and cause even more RH.

So question is…should he try running the fans during lights off period or would the colder air shock the plant? OR is it okay to have such a high humidity during lights off since the temp is so low (could mould still grow in these cold temps with high RH). Swim has grown mushrooms before and know that mould grows in high temp + high humidity but is unsure whether it would still grow in low temp with high humidity.

There is no extra cash to put into the grow and will upgrade the extraction fan, side lighting and also add a dehumidifier during the 2nd and further grows, but for now swim can only run fans and maybe put some more passive de-humidifiers in the closet to try and remedy the high RH BUT swim is unsure whether it would be necessary and needs advise.

BTW: the Jack Harer was grown from a feminized seeds from ILG and in 5th week flower it has a extremely potent lemon smell when touched or gently rubbed, - is this normal for a JH strain?

39" x 24" x barely 5’ tall

I wrote these notes below; As I was reading through you r post. You already know what needs to be done.

Like the balance of 5th week of bloom nutrient schedule. Good air exchange. Good humidity range, until dark and cold. So;

You need a dehumidifier. Shop around on ebay. I found great deals in the past. You can get a unit that allows you to hook it up to a drain line. I grew my 1st 1 LB. plant after getting control of the humidity in the room using a dehumidifier. A dehumidifier unit will also warm up the room; Allowing for a ventilation system; If necessary to allow cool air; If needed.

It will provide an acceptable yield for the $$$ sacrifice.

Hope this helps.

A de-humidifier is TOTALY out of the question for at least another month or 2. There are passive ones as well that are pretty cheap (around $40 down here) and swim really doesn’t want to get those unless he know its going help a bit. Hit and miss takes a lot out of the wallet and right now swim has gone through his reserve funds to get to this point.

As stated above, a de-humidifier + bigger exhaust fan with carbon filter is 1st priority on the upgrade list but its literally impossible to get 1 now. Swim couldn’t even afford a carbon scrubber and is taking a huge chance stinking up the place and risking someone smelling it. Since its only 3 plants he is hoping they wn’t smell so much as to overpower some aerosol spray when visitors come over.

So is there really nothing swim can do except hope they won’t get bud rot in that perfect bud rot environment?

Today swim left the circulation fan running 24/7 and will report back soon on humidity and temperature values. Other than adding those passive calcium chloride tubs with the fan running, swim has no idea what else could possibly help.

I was under the impression you were asking for expert advice. After I give it to you; you call it hit or miss. :frowning: I bought my “killer” humidifier for about 85 bucks on ebay.

Cannabis is an adaptable plant; However; If you cannot afford to grow; or are unwilling to control your environment when you are clearly out of the optimum ranges; You will yield what you yield. The plants will grow as long as they do not wither or become inflames with pests.

I sincerely hole Siwim can cope with these issues until he can buy the necessary environmental tools for a successful grow.

No swim ment hit and miss as in trial and error for things that he’s not sure will work, not for your advice.

Swim know a proper dehumidifier would work because almost everybody uses them but the cost of the unit + the extra cost of electricity wasn’t budgeted for beforehand and he also ran out of funds to get anything extra…but after seeing that even with the fan running he’s still getting 90% RH, he decided that he might borrow some cash from the wife. Swim’s on a different continent so getting something from Ebay might take a few weeks and that may be too late.

Another thing is that for a 2nd hand small portable dehumidifier down here, Is going to set me back for the VERY LEAST $250.

There are Mini portable dehumidifiers for around $50 each but its on special for $90 for 2 units…link below

Swim could go for that but this is where the hit and miss comes in because he isn’t sure if it would work…He has read a few grows of guys using the Eva dry 1100 which is about identical to these units and some have great success while other need a bit more.

If he get 2 units and use both in the closet at lights out? Exhaust fan will be off but circulation fan will be running and temp would be around 15-degrees celcius (58F) at its coldest, could this possibly work until he gets a proper portable dehumidifier? He could always use this in the veg room once the bigger unit for the flower room is purchased?

I really think exhausting air from the tent overnight, even with a dramatic drop in temperature is likely going to be less damaging to a large adult plant than the excessive humidity, just my two cents.

You could also consider reducing the speed of the exhaust fan at night instead of having it completely off. That would also make the temperature drop slower when the lights do go off and reduce shock to the plant from the decrease in temps.

Nice idea MacG…

Eric. Thanks for the clarification, I think that the mini demumidifier in the link would work just fine to start off with. I wish I had the extra funds available to try this unit out. The only thing I see that would require constant attention would be the reservoir. You would need to empty it on a consistent basis in order to keep the unit running. After a couple days, you will be able to figure out a schedule for approximately when res’ would be full.

I concede the “hit or miss” :smiley: Great work.

p.s. I found the evadry unit on ebay. This could work. I also am bidding on a 25 pt. used unit that has a crak in it; So I might get that real cheap. And; Yes, as I recall, my nice 40-50pint unit was a refurbished unit. Similar units are a bit expensive. :slight_smile:

Just for clarification, I understand the temps might get lower overnight than they do with no exhaust overnight, however I stand by my statement that likely the excessive humidity and potential bud rot would be much worse than temperature stress. I think everyone may have understood this is what I meant from my above post, but I just wanted to be extra clear for anyone that did not get that point.

It was plain to me MacG. Perhaps the lower night temps will contribute to unique colors :slight_smile:

Mmm, purple goodness.

Another thought on the temperature swing. All cannabis traces its ancestry to the Hindu Kush mountains of Afghanistan, Pakistan and north-western India. This is a high altitude arid area, that much like other “high” deserts will have dramatic temperature swings between night and day as the thin dry atmosphere allows tons of sunlight to bake down in the day and has little to hold the heat in over the night. From what I understand cannabis should be fine with air temperatures down to as low as 45F or nearly 7C.

Or; Even Lower. Nice post. I did not realize that; I would have thought that there would have been strains in the equatorial regions as well.

Strains from the equatorial regions, yes, but even their ancestry ultimately originates in the Hindu Kush. Kinda like Asian/Indian Elephants’ original ancestry came from Africa.

Yeah, but considering that Cannabis has been around for 1000’s of years; How did it get from Hindu Kush egion to South/Central America? What is your point of reference?

It is the known genetic origin, modern DNA and botanical studies all confirm the original ancestor of all cannabis is from the Hindu Kush mountains. It is also the area known as the silk and spice roads, mankind has been trading and traveling through that area for probably well over 10,000 years, and likely brought it to almost everywhere mankind had settled. It is thought to be one of the very first domesticated plants, going back maybe even before agriculture in the middle east, where the first known large populations supported by agriculture first show up in history around 6,000 years ago.

Thanks for all the comments guys.

The mini dehumidifier came today so swim will be adding it “into” the closet tonight. swim also put some silica gel packs in there. With the exhaust on during lights on, swim doesn’t think it will do much but once lights and exhaust are off then it should contribute a bit. At least swim shouldn’t be getting any condensation in the buds. Even with the high humidity, the buds are looking good and healthy, There is an oscillating fan now as well and it blows between the light and the buds, also is on 24/7 and that has helped a lot.

Swim is a bit concerned that the de-humidifier may not work too well in cold temperatures as it works by cooling warm air and allowing it to condense inside the unit and filling the tub…but with low temps, the air might not be able to cool down further causing very little, if any condensation inside the unit. Either way swim thinks its a good investment in general.

Not sure if the genetic origin would be realistic to follow as some of these plants has been cross bred so many times that those original genes are probably dormant.

Swim will take a few days to observe any changes with the de-humidifier and report back soon.

I think the genetic origins is relevant. Of course almost all cannabis has been crossbred and tinkered with for millennia, however when in doubt I say think about what happens to the plants when mother nature is involved, and even with the tinkering more strains have more in common than they have differences. Also again, it puzzles me as to why there is so much concern over the low temperatures, as we said they do not get anywhere near any truly detrimental temperatures and many people actually do use very low temps to bring out purple in any strain. Many botanical studies have shown pretty much all cannabis can tolerate near freezing temperatures with little detriment if it isn’t for too long, a few hours overnight being of very little concern, and many many places, even besides the hindu kush, grow them outdoors in mountain ranges where the day and night temperatures vary drastically, even the strains grown in southern Mexico are grown in desert like mountain ranges with pretty big changes in temp from night to day. I would be much more worried about the humidity than the temperature ranges you are describing. If you don’t want to take my word for it, check out some botanical studies on it, there are many “non-grower forum”, highly scientific botanical studies that will back up my statements.

BTW, if you can find a copy, I highly recommend the book “Marijuana Botany, An Advanced Study: The Propagation and Breeding of Distinctive Cannabis, by Robert Connell Clarke” and see especially pages 92 section ‘d’ and page 162.

Ok, I’ll try and summarize it real quick for those that can’t get the book, basically on pg. 92, d. it mentions in regards to color and mentions two very different strains from very different parts of the world and different latitudes, a relatively high northern latitude “Indica” original landrace strain from the Hindu Kush region and a near equatorial “Sativa” original landrace strain from the Columbia region and how similar these strains are in regards to temperature despite having been bred for so long in very different environments. The things that the environments do have in common is very arid conditions and similar cold temperatures during the " autumnal" flowering season. So low humidity and some cold temperatures during flowering.

And on page 162 it specifically mentions temperature extremes and cannabis, in general, being able to even survive a light frost as long as it doesn’t last very long as well as some interesting studies on dramatic root and stem temperature variations, i.e, stems and roots both being 30c or roots and stems both being 15c vs. various combinations, i.e. stems at 15c while roots are at 30c and vice versa.