I’m looking for opinions on what factors are the most important to plant health when you can’t furnish the ideal environment.
I’m in early veg. My biggest challenge is humidity/temp/vpd balance. If I lower my airflow, the tent can go as high as 85 degrees. With my humidifier I can get it to about 48 RH. With more airflow to get it under 80 degrees, my humidity then drops to about 40%RH. In both cases VPD is 2 - 2.2.
During lights out it goes to about 70 degrees and 50-55% RH.
So not sure what I should focus most on.
2nd grow.
2x4 tent.
Autoflowers - CBD Purple Kush (1:1) and Slutty Runtz.
20/4 cycle. 4100K. 550/39 PPFD/DLI
Mars FC-4000 light.
Cloud Coir 50/50 in air pots.
Fertigation using General Hyroponics nutes at medium/early grow strength. ~ 1200EC/600ppm
Only a couple days in tent, have not measured runoff.
Girls were a bit low on Nitrogen before I transplanted 2 days ago, or so it seems by slight yellowness.
Hi. I had constant low humidity during this grow and in flower now. They’ll be just fine. When they get bigger, you’ll be looking for ways to maintain low humidity because they let off water constantly.
Right now, temp for me is more important. I like to grow around 70 to 75F early on.
Unless your humidity is 40 with 1 week old seedlings or lower than 40 in general they will do fine.
Just be careful to balance out feedings and maintain good watering schedule for now.
Turn down the dehumidifier. Anything below or around 65% RH is fine for now, once they begin to flower, then keep it closer to 50% RH.
If you don’t have a controller that triggers off of VPD, you can drive yourself crazy with it. If you do, make sure the offset is calculated. The 2.2 seems really high, like an off set may not be entered.
I shoot for a temp between 75 / 83f, with a RH <65% at the size your plants are. Maintain the temp but drop the RH to >55% after a few weeks of flower. The last 3 weeks before harvest, drop the temps to 70f and RH to >50%.
You’ll see spikes when lights out after feeding, night time and other things. AS long as it comes back into range in an hour or so, (I prefer less) don’t sweat it.
Chasing vpd can be hard. I don’t bother. The plants can grow well in a wide range. There may be a sweet spot on the charts but they will grow fine outside the optimum range too.
As was stated the humidity will rise once the plants get bigger. They will transpire a lot of water.
I am wondering what your solution pH is? 5.8 is the spot coco coir likes. The lower yellow leaves should not be happening this early.
I used to be a big proponent of VPD but not these days…too many issues for me.
Now I typically run my spaces on the drier side to avoid PM and other related issues…in fact I’ve had a dehumidifier running 24/7 on this run keeping me at about 40% RH.
I run the Mars hydro sp3000 it gives the advantage of removing the very very hot transformer outside the tent to keep the inside of the tent a lot cooler. I don’t know if you would have to rewire a little bit but in my experience well worth it. I also have a 2x4 tent.
I got a question for you, when you water with using those pots does it come through all the little Spike holes like it’s peeing? I thought about getting fabric bags around those pots. I seen someone put fabric around those so when water does sprout out it will hit the fabric and trickle straight down. Just curious thank you
Dang I can’t read. Apologies @cc014572 I could swore you said “dehumidifier”. Everything I said before still applies, just not as simple as turn down the “dehumidifier.”
Where is your tent drawing fresh air from?
Are you using a “lung room”?
Where do you have the hygrometer sensor? Are you using the one hanging between the girls? If so have you verified the readings with a second unit?
Hi. My tent draws air directly from the basement and vents directly outside the house as my wife hates the wonderful cannabis smells.
My RH varies depending on the outside weather and how much the heater/AC runs. So when it runs a lot my RH is 35-40%. When it does not run during the day at all, like when it’s 70 degrees outside, the RH goes to about 50%.
Hi, I have my transformer outside the tent also. It gets pretty hot.
For the air pots, nothing comes out the side holes at all. It drips into my drain pans then into my jugs. I got tired of gross fabric bags so I thought I would try these this time as I can reuse them easily.
Thanks. I don’t see way to hit “ideal” vpd targets, at least with my setup. So I’ll ignore all that. My basement RH is a pain. In winter/early spring if we get a lot of rain it goes to 55-60%. That happened last grow at 9 weeks into flower. Went out and got a fairly good dehumidifier and got things down to 40-45%. I was paranoid about mold/fungus that late,
I’ve got an automatic watering system I’m going to hook up when they get bigger and pull more water. Right now fertigating once a day with a quart each still producing good run off. Looking forward to seeing how the air pots work.
