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- #61
Metalfish
Well-Known Member
I just googled it, I just went and made a few adjustments, I’ll check it later..
Thanks for bringing it to my attention
With a $12000+p/a Script - I Need To Grow a Little
- Thread starter Metalfish
- Start date
Thanks for bringing it to my attention
Delps8
Well-Known Member
At that stage, early veg, I'd be at 29°C/85°F and RH of mid-60's.
It's fine to think in terms of ranges of temperature and RH but I find it easier to think in terms of vapor pressure deficit ("VPD").
For humans, we use the terms "feels like" temperature because we do better when RH isn't either very high or very low. If RH is high, sweat doesn't evaporate and it feels hot and muggy. If it's really dry, we sweat a lot and have to drink more water.
Plants have a similar reaction but it's not sweating, it's "transpiring" and keeping things in the mid-range is good because plants take up nutrients when the transpire. If it's hot and/or dry, they have to transpire a lot so they take up more nutrients. On the other hand, if it's cool and/or moist, they can't transpire so they may not take up enough nutrients.
VPD is just a number that indicates a range of temperature and RH values. For early veg, a VPD of 1.0 works well. Check out the VPD chart here and you'll see the different combinations of temperature and RH that all make up a VPD of 1.0. As long as you're in that range, the plants will transpire well.
From the perspective of VPD, 20/68 is OK as long as RH is about 50 (that's the green zone for 68°F. But at 68°F, the plants' metabolism slows waaaaay down.
A very good approach (the optimal value for maximizing crop yield) is to have leaf temps at 80-85°F through veg and into about the second week of flower. The high temp will increase the metabolic rate of the plant so that it can build out the branches and leaves that it will need for the flowering phase.
Once build out is complete, which is about the second week of flower, drop the temperature in the tent so that the temps at the flower tops is no more than 25/78 and if you can drop it into the low or mid-70's (21-25) even better.
The lower temperature in flower helps retain the cannabanoids whereas, with the higher temps, cannabinoid levels will drop significantly.
There's no need to adopt using VPD and some growers actually rail against it. I use it because I'm comfortable with the concept and because a lot of growers, myself included, use automation devices that control fans, heaters, and humidifiers to try to keep temperature and RH at optimal levels.
Back to your plants - them them up to 27 or a bit higher, get RH into the 60's, and they'll grow quite a bit better.
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- #63
Metalfish
Well-Known Member
Thanks mate, very helpfulAt that stage, early veg, I'd be at 29°C/85°F and RH of mid-60's.
It's fine to think in terms of ranges of temperature and RH but I find it easier to think in terms of vapor pressure deficit ("VPD").
For humans, we use the terms "feels like" temperature because we do better when RH isn't either very high or very low. If RH is high, sweat doesn't evaporate and it feels hot and muggy. If it's really dry, we sweat a lot and have to drink more water.
Plants have a similar reaction but it's not sweating, it's "transpiring" and keeping things in the mid-range is good because plants take up nutrients when the transpire. If it's hot and/or dry, they have to transpire a lot so they take up more nutrients. On the other hand, if it's cool and/or moist, they can't transpire so they may not take up enough nutrients.
VPD is just a number that indicates a range of temperature and RH values. For early veg, a VPD of 1.0 works well. Check out the VPD chart here and you'll see the different combinations of temperature and RH that all make up a VPD of 1.0. As long as you're in that range, the plants will transpire well.
From the perspective of VPD, 20/68 is OK as long as RH is about 50 (that's the green zone for 68°F. But at 68°F, the plants' metabolism slows waaaaay down.
A very good approach (the optimal value for maximizing crop yield) is to have leaf temps at 80-85°F through veg and into about the second week of flower. The high temp will increase the metabolic rate of the plant so that it can build out the branches and leaves that it will need for the flowering phase.
Once build out is complete, which is about the second week of flower, drop the temperature in the tent so that the temps at the flower tops is no more than 25/78 and if you can drop it into the low or mid-70's (21-25) even better.
The lower temperature in flower helps retain the cannabanoids whereas, with the higher temps, cannabinoid levels will drop significantly.
There's no need to adopt using VPD and some growers actually rail against it. I use it because I'm comfortable with the concept and because a lot of growers, myself included, use automation devices that control fans, heaters, and humidifiers to try to keep temperature and RH at optimal levels.
Back to your plants - them them up to 27 or a bit higher, get RH into the 60's, and they'll grow quite a bit better.
Thank you
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- #64
Metalfish
Well-Known Member
If I understand correctly?At that stage, early veg, I'd be at 29°C/85°F and RH of mid-60's.
It's fine to think in terms of ranges of temperature and RH but I find it easier to think in terms of vapor pressure deficit ("VPD").
For humans, we use the terms "feels like" temperature because we do better when RH isn't either very high or very low. If RH is high, sweat doesn't evaporate and it feels hot and muggy. If it's really dry, we sweat a lot and have to drink more water.
Plants have a similar reaction but it's not sweating, it's "transpiring" and keeping things in the mid-range is good because plants take up nutrients when the transpire. If it's hot and/or dry, they have to transpire a lot so they take up more nutrients. On the other hand, if it's cool and/or moist, they can't transpire so they may not take up enough nutrients.
VPD is just a number that indicates a range of temperature and RH values. For early veg, a VPD of 1.0 works well. Check out the VPD chart here and you'll see the different combinations of temperature and RH that all make up a VPD of 1.0. As long as you're in that range, the plants will transpire well.
From the perspective of VPD, 20/68 is OK as long as RH is about 50 (that's the green zone for 68°F. But at 68°F, the plants' metabolism slows waaaaay down.
A very good approach (the optimal value for maximizing crop yield) is to have leaf temps at 80-85°F through veg and into about the second week of flower. The high temp will increase the metabolic rate of the plant so that it can build out the branches and leaves that it will need for the flowering phase.
Once build out is complete, which is about the second week of flower, drop the temperature in the tent so that the temps at the flower tops is no more than 25/78 and if you can drop it into the low or mid-70's (21-25) even better.
The lower temperature in flower helps retain the cannabanoids whereas, with the higher temps, cannabinoid levels will drop significantly.
There's no need to adopt using VPD and some growers actually rail against it. I use it because I'm comfortable with the concept and because a lot of growers, myself included, use automation devices that control fans, heaters, and humidifiers to try to keep temperature and RH at optimal levels.
Back to your plants - them them up to 27 or a bit higher, get RH into the 60's, and they'll grow quite a bit better.
After yesterday’s adjustments my tent is now at 23.5’c and RH 64% it has to be better, doesn’t it?
I have my grow tent in an outdoor toilet room, so my heating is limited. We are about to hit spring over here and it will get warmer.
Delps8
Well-Known Member
Most definitely.
The chart below is from a research paper on cannabis. The focus of the research was on how net photosynthesis ("net P") changed with as CO2, temperature, and light levels changed. It was mistakenly interpreted to indicate that there was little reason to increase light levels beyond 500µol (see footnote) but the reason I've posted it is to show the change in net P as temperature changes.
At any light level, PPFD, the photosynthetic rate at 20° was 8± which was about the same as it was at 40°. By raising the temperature to 25°, that value went to 14. The rate of net photosynthesis is a valid proxy for growth of the plant so, if you can bump it up a bit more, you'll end up with more growth but just going from 20° to 25° is a huge jump.
And, if you can increase light levels, you'll get another jump in both the growth rate and the yield. The yield curve is in the table I've created (the source is cited). The yield curve does roll off but it's about a 5% increase in dry weight for every 50µmol increase in PPFD at lower light levels, dropping to about 4%. Raising average PPFD from 700µmol to 900µmol showed almost a 20% increase which pretty good for just turning up the dimmer.
*Growers argued that this paper shows that there's little value in increasing light levels much above 500µmol. When I first read this paper, I thought, "Well, that's interesting but I'm not harvesting photosynthesis.". Subsequent research directly addresses that fallacy and clearly demonstrates an increase in crop yield, not "net P", as light levels increase.
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- #66
Metalfish
Well-Known Member
Holy shitMost definitely.
The chart below is from a research paper on cannabis. The focus of the research was on how net photosynthesis ("net P") changed with as CO2, temperature, and light levels changed. It was mistakenly interpreted to indicate that there was little reason to increase light levels beyond 500µol (see footnote) but the reason I've posted it is to show the change in net P as temperature changes.
At any light level, PPFD, the photosynthetic rate at 20° was 8± which was about the same as it was at 40°. By raising the temperature to 25°, that value went to 14. The rate of net photosynthesis is a valid proxy for growth of the plant so, if you can bump it up a bit more, you'll end up with more growth but just going from 20° to 25° is a huge jump.
And, if you can increase light levels, you'll get another jump in both the growth rate and the yield. The yield curve is in the table I've created (the source is cited). The yield curve does roll off but it's about a 5% increase in dry weight for every 50µmol increase in PPFD at lower light levels, dropping to about 4%. Raising average PPFD from 700µmol to 900µmol showed almost a 20% increase which pretty good for just turning up the dimmer.
*Growers argued that this paper shows that there's little value in increasing light levels much above 500µmol. When I first read this paper, I thought, "Well, that's interesting but I'm not harvesting photosynthesis.". Subsequent research directly addresses that fallacy and clearly demonstrates an increase in crop yield, not "net P", as light levels increase.
I have to much opioid brain fog to concentrate, this is high tech stuff
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- #67
Metalfish
Well-Known Member
My little babies got topped today
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- #69
Metalfish
Well-Known Member
I was a bit slack, I forgot to take my phone out with me so, tomorrow.
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- #71
Metalfish
Well-Known Member
Here they are topped
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- #72
Metalfish
Well-Known Member
Day 21, looking ok but must be lacking something as the leaves aren’t as green as they should be.
Turned light up to 50%
Turned light up to 50%
TassieTurtleman
Well-Known Member
The garden is looking awesome metal!
Great job
Great job
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- #74
Metalfish
Well-Known Member
Cheers mate
TassieTurtleman
Well-Known Member
Keen as to start my gorilla girls, hopefully mine look as good as yours!!
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- #76
Metalfish
Well-Known Member
Yeah mate the GG is the one at the back with the big leaves. They both have yellow in their leaves but not sure what they are needing.
I was reading over on your post that you’ve been getting crap weather. We’ve been getting blown away here. I’m glad mine are indoors cause a lot of our outdoor pot plants have been blown over.
TassieTurtleman
Well-Known Member
Hmmm I can't really see much yellow in the pics? Maybe it's just the light isn't showing it. Yeah we had good weather for a couple weeks, so I was like this is great. Glad I held off on germination, as we been getting smashed with cold temperatures, rain and wind nearly every day, but apparently in 2 weeks, it's gonna be really good! I don't have the option to move my girls inside, so I have to be really careful with that
They're looking great. I'd say they're a little light in magnesium, or they're just hungry in general.
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- #79
Metalfish
Well-Known Member
Mate we’ve had beautiful sun but with blow your wheelie bin down the street winds.
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- #80
Metalfish
Well-Known Member
I’m in the zone at the momentAt that stage, early veg, I'd be at 29°C/85°F and RH of mid-60's.
It's fine to think in terms of ranges of temperature and RH but I find it easier to think in terms of vapor pressure deficit ("VPD").
For humans, we use the terms "feels like" temperature because we do better when RH isn't either very high or very low. If RH is high, sweat doesn't evaporate and it feels hot and muggy. If it's really dry, we sweat a lot and have to drink more water.
Plants have a similar reaction but it's not sweating, it's "transpiring" and keeping things in the mid-range is good because plants take up nutrients when the transpire. If it's hot and/or dry, they have to transpire a lot so they take up more nutrients. On the other hand, if it's cool and/or moist, they can't transpire so they may not take up enough nutrients.
VPD is just a number that indicates a range of temperature and RH values. For early veg, a VPD of 1.0 works well. Check out the VPD chart here and you'll see the different combinations of temperature and RH that all make up a VPD of 1.0. As long as you're in that range, the plants will transpire well.
From the perspective of VPD, 20/68 is OK as long as RH is about 50 (that's the green zone for 68°F. But at 68°F, the plants' metabolism slows waaaaay down.
A very good approach (the optimal value for maximizing crop yield) is to have leaf temps at 80-85°F through veg and into about the second week of flower. The high temp will increase the metabolic rate of the plant so that it can build out the branches and leaves that it will need for the flowering phase.
Once build out is complete, which is about the second week of flower, drop the temperature in the tent so that the temps at the flower tops is no more than 25/78 and if you can drop it into the low or mid-70's (21-25) even better.
The lower temperature in flower helps retain the cannabanoids whereas, with the higher temps, cannabinoid levels will drop significantly.
There's no need to adopt using VPD and some growers actually rail against it. I use it because I'm comfortable with the concept and because a lot of growers, myself included, use automation devices that control fans, heaters, and humidifiers to try to keep temperature and RH at optimal levels.
Back to your plants - them them up to 27 or a bit higher, get RH into the 60's, and they'll grow quite a bit better.