Need a doctor

Kassiopeija said:

but the pot isn't light at that time, you could save yourself some hassle and just let it dry out more, and observe a correct dry-water cylce. It is possible, when the rootsystem is fully established, entirely filling the pot, to water more often, esp. under strong lights, but seeing you have these problems it's best to stick to the standard rules.


It's not the Epsom that's problematic but rather the water and increased rH that may provoke mold....


Calmag in your water is enough, a good product should have a ca:Mg ratio of 3:1 - 2:1. One can add a bit of Epsom when the plants call for it, but it's more easy for plants to just stick with what works. Constantly changing stuff does more damage than good IMO...

Greets


Yeah, 20% runoff guarantees the old nutes gets out of the pot... plants don't always take in all of that stuff, they have some minor selective control and the roots can also "spit out" excess/unwanted stuff back - which shouldn't accumulate in the root zone.

Well done!

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HydroKid239 said:

I agree with everything said here. I have a question tho.. it may also be informative for the OP as well.. you said the plants don’t always take up all we feed into the soil.. but.. my question is..

Would the plants take up more & leave less excess by next feeding if the environment is dialed in correctly with a VPD chart?
While reading on VPD I see something about it affecting nutrient uptake. That begs my second question… Can a VPD “out of whack” possibly burn plants that haven’t been over fed?
I’m still fairly new to growing, and most of the time I wing it.. and things turn out awesome. I’d like to stop winging it lol Your time & knowledge is much appreciated.

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Boatguy said:

Is the op even here anymore?
VPD is for people that have a dialed in grow. If you cant grow a healthy plant it wont help you.
I, and many here have grown great pot without even knowing what vpd is.

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HydroKid239 said:

That doesn’t answer my question, but I appreciate the obvious input.

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Boatguy said:

Didnt mean it to come off wrong.
So yes if your temps and humidity are horrible you can expect the same result in your grow.
You can be far off a vpd chart and still grow a decent plant.

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HydroKid239 said:

Can a VPD “out of whack” possibly burn plants that haven’t been over fed?

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Kassiopeija said:

well, one could argue that a plant that is nutrient tox has been overfeed by definition and it's rather to adjust the feed given and adapt it to the demand of a plant in its current situation than to try to adapt the plants environment to the feed given.

VPD itself seems a bit clunky. When I measure leaf surface temps I get abberrations of +-5°C easily between leaf A B C.... dark leaves, highly saturated in nutrients are always warmer... now it would seem counter-intuitive to me to try to fiddle with rH/temps just because the feedstrength was upped due to the plant getting more bright/ hungry.
And there are many factors involved in stomatal conductance, even nutrient related, I guess VPD isnt the full story.

But to address your initial question, it's transpiration rate that increases passive nutrient intake ie. "drinking". That's nute intake not by ion exchange. If you wanna know more about this the keywords are "symplastic" & "apoplastic" nutrient assimilation.
For sure the environmental factors can influence nutrition demand but temperature affects a number if things, for example, the rate how microbes release nute ions, so from my point of view it seems impossible to make a broader general statement here.

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