Very poor growth on 3 of 4 plants.

FirstCavApache64

FirstCavApache64

Well-Known Member
agare$969 said:
Thanks for all the info man. Im going to read that directly! Tbh my humidity is about 70% I believe. According to my analog meter which isn't super accurate so I'd say between 65-75%. I do have a temp gun. Is there an equation to measure vpd using ambient temp, leaf temp and humidity? I've been growing in coco with 3 daily feedings using dyna gro grow and cal mag on 3 of the 4 and just the grow on the super dark one bc it looks like a nitrogen abundance so I backed off a little and it's seemed to have lightened the leaves up some.
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Here's a link to a good VPD chart.
vpdchart.com

VPD Chart

Vapor pressure deficit (VPD) chart & calculator for horticulture in controlled environment. Cannabis, tomatoes, leafy greens, cucumber.
vpdchart.com vpdchart.com
You just enter in the data and it plots the VPD value for you.
 
drsaltzman

drsaltzman

Well-Known Member
I wouldn’t be worried about vpd with plants that small.
These plants look overwatered and locked up.
 
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Roadblock007

Well-Known Member
drsaltzman said:
I wouldn’t be worried about vpd with plants that small.
These plants look overwatered and locked up.
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Size doesn't matter if your VPD is too far out, they wont transpire and that compounds everything else, in clones or seedlings if the air is too dry they shut down if your salt is a little too hot as they don't have the root capacity to draw enough moisture that the dry air is pulling out of them, if it's over humid they drown as they cant get rid of the moisture, both deals will end with lockouts, you don't have to be perfect but you got to be close and aware of how the plant reacts when its not right.

I agree with the over watering, they don't need much when they are little, having them transpiring is extremely important in the way they handle moisture in the medium, the difference between thriving and bogging down.
 
drsaltzman

drsaltzman

Well-Known Member
I’ve never subscribed to the VPD craze. I suppose it’s not much different than cooking.
Some people measure everything. Some people just have the touch.
But if it works for a grower, or if they find it fun and interesting, I’m all for it. Whatever gets you through the grow.
This one is just a case of doing too much. Pretty common with new growers. Haven’t developed that restraint yet.
 
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Roadblock007

Well-Known Member
The thing is if you're going ok your VPD is generally not far out, its not really a craze its just growers looking for the highest yields woke up to it because its well proven scientific fact, the top commercial guys are right on it because it's very important if you want your full potential, it's a bit like restricting air into your carburettor, no matter how much fuel you pour into the cylinder its won't burn if it doesn't have the air ratio it needs for the amount of fuel, for the plant it needs the right osmotic balance to turn over your nutrient at maximum uptake.

I guess it all depends if you want maximum or not, I dont know how many times Ive seen struggling plants and the vpd was way off. lots of guys will be careful not to over water seedlings clones in small rockwool cubes or cups and this small volume of nutrient can cause the EC to spike very quickly, then if your vpd is on the dry side the plant cant move the water so now they have all this cupping and twisting that compounds into root issues, next they are nursing plants trying to get them fire.

Growing plants is a balancing act of everything, if one thing is out the whole system is held back to that one thing that's wrong.
 
agare$969

agare$969

Member
Got these guys in a tent finally. Got em topped and have some clones sitting in a little propagator at about 7,000 lux. pH and ppm are on point at 5.9 and ppm is 500 or 1.0 EC. Since getting this info on keeping my run off at 5.8-6.2 and ppm from 500-600 I've seen significant improvement in all my plants. What was a serious nute deficiency is now back on point. The leaves on the bigger girl have gotten so much darker and look much healthier. I brought the smallest one back from a shriveled up pile of leaves. I couldn't be more grateful for the advice Ive gotten on here. It definitely saved me so much headache and I now feel confident in the final product and getting to turn around and start over with these few clones that hopefully root. I added some clonex and then planted in some coco and perlite mix. No nutes yet as they were planted 3 days ago.
 

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agare$969

agare$969

Member
Thanks a lot for the info again. I try my best. I water 3 times daily without fail and since getting my ppm/EC and pH dialed in it's been all uphill. I've tried to prune the best I could as to direct the plants energy upward to bud sites. Those pics were from last week. I just flipped last night and this is what they looked like yesterday. Also, how should I water in 12/12 if they need complete darkness? I know it's probably a dumb question but ya can't learn if you don't ask. Lol. Thanks again for the positive affirmation fellas. Sorry if the pic quality is shitty. It's a screenshot from a video I took. When the lights come on I'll get some better pictures.
 

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agare$969

agare$969

Member
I couldn't have made it this far without the extensive knowledge everyone was nice enough to to proved me with. It's always been fascinating watching growers do their thing and I never thought I'd have the patience. Low and behold I found some patience and there's no end In site now. I have 4 clones going too so maybe I'll have a few viable ones so I can start over when I'm done flowering. Question. If I pull clippings from a plant in flower, will I have to revert that clipping back to veg?
 
bk78

bk78

Well-Known Member
Roadblock007 said:
Nothing wrong with coco its a great medium, its probably the balance of things in your room that is out of wack.

VPD is very important, probably the most important single aspect of it all, if this is out the plant does not transpire as it should, then shit starts happening.
Irrigation volume and cycle. read some stuff on crop steering to get your head around irrigation.
Nutrient strength, no point running full nutrient if the plant is not transpiring at maximum.

If these are not dialled in for your particular grow space expect a chain reaction of things to show up.
Click to expand...
What did the world do for decades before the VPD chart was made a couple years ago?
 
agare$969

agare$969

Member
FirstCavApache64 said:
Great job on getting them into shape for flower. Keep up the good work!
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I've also flipped to 12/12 yesterday. I was thinking about changing the time from 8a-8p so they don't need watered at night. I water 3 times daily to 10-20% runoff with every feeding. I don't have a pump or anything to remove the water from my tent so I have the pots on some trays so they don't sit in stag water but it's changed daily. My question is, bc I switched to flower and the schedule is different (lights on at 5 off at 4) so I'm doing 13/11. I know letting light in on flowering plants is detrimental to yields and a bunch of other things so that's the last thing I wanted but how does one water in the dark. I'm hand watering and I have to physically remove the plants to drain the water bc I have no pump which I am purchasing today. Here's some pics of them this morning. The little girl came back from literally a shriveled up leaf but I never gave up on her.
 

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