HarveyHarvester
Well-Known Member
Is this applicable to cannabis?
Last edited:
Vapor Pressure Deficit?
- Thread starter HarveyHarvester
- Start date
CaptainCAVEMAN
Well-Known Member
Yes
HarveyHarvester
Well-Known Member
Even in flower at 75F I want RH @ 65% - 70%?
Am in late flower now at 75F with RH as low as I can get it, currently running around 30% - 40%.
So I'm doing it wrong?
I'm a rookie.
Am in late flower now at 75F with RH as low as I can get it, currently running around 30% - 40%.
So I'm doing it wrong?
I'm a rookie.
Last edited:
HarveyHarvester
Well-Known Member
Thanks man. Mold was in fact my concern with that.
Dr. Who
Well-Known Member
@HarveyHarvester
In a kind of longer answer...
Yes and No! That one is fine but what you need to know of in a more scientific light but, with simple terms-goes like this...
In general, unless your running Co2. Keep your RH at around 50% I set my dehum's at 45 and they have about a +/- of 5%.
The more lower you go in RH the more the plant transpires. That means in simple terms it will use more moisture from your "media" faster. This also means that you have "more" or increased up-take of nutrients. The more and faster up-take can and does effect the amount of nutrient you use to feed with. That reflects the fact that "more and faster" up-take means less nutrient should be used to some point as you could get an "overfeeding" condition.
MOST nutrient makers formulate nutrients for use in a 45 - 55% RH range. Below 40 simply begins to put stress on the plant to try and keep up the transpiration at a rate to not let the plants leaves dry out...
Room temps are a factor in this too! An overall room temp of around 75 F is great. The hotter it gets - the more the plant will transpire......When you run Co2 at 1500ppm. Your temps should be around the low 90's and RH around 75 - 85% RH. That now match's the chart much better as the gas is unlocking the the ability of the plant to reach it's "potential"......You should now that you can do the potential reaching with out gassing! That's an ability that comes with experience..
Good Luck!
In a kind of longer answer...
Yes and No! That one is fine but what you need to know of in a more scientific light but, with simple terms-goes like this...
In general, unless your running Co2. Keep your RH at around 50% I set my dehum's at 45 and they have about a +/- of 5%.
The more lower you go in RH the more the plant transpires. That means in simple terms it will use more moisture from your "media" faster. This also means that you have "more" or increased up-take of nutrients. The more and faster up-take can and does effect the amount of nutrient you use to feed with. That reflects the fact that "more and faster" up-take means less nutrient should be used to some point as you could get an "overfeeding" condition.
MOST nutrient makers formulate nutrients for use in a 45 - 55% RH range. Below 40 simply begins to put stress on the plant to try and keep up the transpiration at a rate to not let the plants leaves dry out...
Room temps are a factor in this too! An overall room temp of around 75 F is great. The hotter it gets - the more the plant will transpire......When you run Co2 at 1500ppm. Your temps should be around the low 90's and RH around 75 - 85% RH. That now match's the chart much better as the gas is unlocking the the ability of the plant to reach it's "potential"......You should now that you can do the potential reaching with out gassing! That's an ability that comes with experience..
Good Luck!
RM3
Well-Known Member
Been teachin this for years, surprised it doesn't get spread more 
adjust your garden using the heat index, and yes it's kinda like lumens more about how humans feel heat but it works a charm
Coolest thing about it is it lets you adjust that which is easier to adjust, either the temps or the humidity or both.
You want a heat index that is 4 points above ambient !!!
here is a calculator, http://www.easysurf.cc/cnver16.htm
as example a temp of 90 requires a RH of 50% which will give you a heat index of 94.6
a temp of 72 requires a RH of 33% (better for tric production) which gives you a heat index of 76.5
Simply play with numbers, adjust what you can to get that 4 point spread, your plants will love you for it
adjust your garden using the heat index, and yes it's kinda like lumens more about how humans feel heat but it works a charm
Coolest thing about it is it lets you adjust that which is easier to adjust, either the temps or the humidity or both.
You want a heat index that is 4 points above ambient !!!
here is a calculator, http://www.easysurf.cc/cnver16.htm
as example a temp of 90 requires a RH of 50% which will give you a heat index of 94.6
a temp of 72 requires a RH of 33% (better for tric production) which gives you a heat index of 76.5
Simply play with numbers, adjust what you can to get that 4 point spread, your plants will love you for it
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