Originally Posted by kowhite
Heady - Happy belated birthday bro! How I missed that the other night I do not know.
Growaway - I second heady's statement...awesome post, super informative. I've got a few little ones growing now and I've been applying the knowledge I've gained regarding VPD to how I manipulate the environment with satisfyingly effective results. They're currently residing in a 4x7 grow tent while construction of their new and bigger home is under...of which I am super excited about (shout out to Heady Blunts for helping me to finalize the design) I will post pics for all who are interested soon. There are a couple of terms that you've used in your posts that I am not as familiar with as I'd like to be and was hoping you wouldn't mind elaborating...temperature differential and mean temp. As simple a term they may be if you wouldn't mind breaking them down to me (and the rest of us) as though I (and not the rest of us) were an idiot it would be much appreciated.
Waxy - what up man...how's the room going? Figure out that whole furnace fucking shit up ordeal? The hours I spent reading/posting in your lung room thread were very informative times in the life of kowhite...
Peace and CBD grease.....
Cheers Kowhitee, thanks for the shoutout. Mean Temp. is the just average temp of the grow space across the course of 24hrs. If you were to sample temp each hour and add these values together, then divide by 24, you would get your mean temp. Temp differential is the difference between maximum temp and minimum temp. in a 24hr period. For example, if max 85F during the day and min 55F at night = Tdiff of 30F. Wider temp diffs and overall higher means temps are generally considered a generative measure in the grow space once flowering/fruiting is underway. These measures encourage assimilates towards flowering and fruiting plant parts in preference to the foliage provided the flower/fruit load dominates plant balance. Used appropriately, a very vegetative, slow n short, lower yielding variety can be encouraged to improve flower development and plant structure. Used poorly, or with the wrong variety, and you will get stretch like a bitch and/or "exhausted" plants that don't reach their genetic flowering potential.
Creating greater temp diffs that increase the overall mean temp tends to accelerate assimilate production and stretch and potentially improve yield(think warmer day temps with nights staying same). Greater temp diffs that lower the mean temp can reduce assimilate production and slow development and reduce stretch(think colder night temps with days staying the same).
These changes are relative to the 'normal' temps that you would use for a particularly strain for example with light intensity, CO2, and feed manipulation used to assist the process.
All this is great provided you have the ability to change and completely control day and night time temps (active heating and cooling systems). For most of us at home, we see the effects of on our plants of our inabilty to control changing mean temp and Tdiff. In our effort to correct it, we may smash our VPD to shit. Commercially, hydronic heating and evaporative fogging and/or A/C cooling systems are the growers friend but are not cost viable for most us at home. One day...
Still, knowing about it and doing what we can do to control or manipulate it can be the difference between an average result or a great one particularly under difficult climate conditions.
Once again, i have been asked a simple question and turned it into a wall of text. This new OG pheno i have just sampled could possibly be to blame...makes me rave on just a tad.
Cheers and thanks.
PS. 102F max temp in my part of the world today! Misting, irrigating, shading and venting time! Yehaaa!