SQl2kGuy
Well-Known Member
I guess it is the uncertainty of the first grow for newcomers that cause all the questions. I ask a ton!
Keep asking questions and reading journals ... there's a lot you can do for your plants.
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I guess it is the uncertainty of the first grow for newcomers that cause all the questions. I ask a ton!
Excellent point @TurboBucket ... the chart I have points to that saying ... "VPD when leaves are 2°C (4°F) cooler than air temperature"
Yes the Leaf temp to Ambient DIFFERENCE is a key VARIABLE in the chart readings ALONG with the
GROW STAGE
I have been using the CHART above with the -2c readings BTW there is a -1c chart as well that I used
to calculate out the Difference for A ZERO leaf to ambient difference.
(Move the ANSWER 4 places to the right for zero difference)
Also found using HID & T5s I need canopy to be at 21 inches below HID for the -2c
Yes the Leaf temp to Ambient DIFFERENCE is a key VARIABLE in the chart readings ALONG with the
GROW STAGE
I have been using the CHART above with the -2c readings BTW there is a -1c chart as well that I used
to calculate out the Difference for A ZERO leaf to ambient difference.
(Move the ANSWER 4 places to the right for zero difference)
Also found using HID & T5s I need canopy to be at 21 inches below HID for the -2c
Had the chart enlarged and printed at Kinkos just enough room to add the F readings
Hey @Gazoo ... I'm glad you popped in and pointed that out.
I have been assuming that my leaf temperatures were around 2°C (4°F) below ambient. I'll buy the temperature gun one day though to do canopy readings.
Actually, this week when I let the canopy drop below 30 cm (12") ... the leaves hated it and started to curl.
Alright ... ttyl
Hey @thebigearl ... I'm glad you have no issues.
You could likely drop the RH a bit and be safer with better growth rate.
Here's a good article from our Sponsor ... if you're interested ... Indoor Cannabis Growing: Relative Humidity and Temperatures
I guess it is the uncertainty of the first grow for newcomers that cause all the questions. I ask a ton!
Just so we don't all get hung up on the VPD thing. I know it's important, but I've just harvested dried and trimmed a few plants grown in 32-35C and 60-95%RH for the entire flower cycle.
My yields were 1.3 g/watt - didn't really change much on the yield thing.
I do have some experience so I knew to keep A LOT of air moving and exchanging in the flower room as well as taking preventative measures for mold/pm.
Southern Ag - Garden Friendly Fungicide - its an organic bacteria that eats mold and the spores.
I had no mold and no PM and my plants were happy most of the time.
So like I mentioned, use those charts as a guide and don't get crazy if you exceed the sweet spot every now and again. It's not going to be the end of your grow.
I'm sure the hot summer sun at noon time temps far exceed 35C at the leaf surface outdoors. The plants will change the angle of the leaves so they don't absorb the full amount of radiation. Just another function of leaves.
In regards to "Southern Ag - Garden Friendly Fungicide". Is this something that can be sprayed weekly up to harvest.Just so we don't all get hung up on the VPD thing. I know it's important, but I've just harvested dried and trimmed a few plants grown in 32-35C and 60-95%RH for the entire flower cycle.
My yields were 1.3 g/watt - didn't really change much on the yield thing.
I do have some experience so I knew to keep A LOT of air moving and exchanging in the flower room as well as taking preventative measures for mold/pm.
Southern Ag - Garden Friendly Fungicide - its an organic bacteria that eats mold and the spores.
I had no mold and no PM and my plants were happy most of the time.
So like I mentioned, use those charts as a guide and don't get crazy if you exceed the sweet spot every now and again. It's not going to be the end of your grow.
I'm sure the hot summer sun at noon time temps far exceed 35C at the leaf surface outdoors. The plants will change the angle of the leaves so they don't absorb the full amount of radiation. Just another function of leaves.
Edit - here's my flowers in 35C temps and +70% RH