Question regarding Ca uptake in early flower and VPD

[jackspratt61]

the way i look at humidity is a shield. it allows you to run the temp you want high enough so that transpiration is peak and stomata is open to ideal amount. lowering that shield increases transpiration at first but once it crosses over to the dark side the stomatas close as an emergency intervention to slow water escaping.in turn stops calcium from being mobile but also can lockout other nutrients due to cascade effect on taking up too much too fast. thats where leaf surface temp really comes into play. similar to chuggin a milkshake leads to stomac ache.

its hedgin your bets compared to how often your able to refresh roots with feed. so there are inhibitive dangerous zones at too dry or too moist and then a sweet spot zone which you can choose either aggressive(less) or safe(high) rh levels. it is also strain dependent to a point. lowland plants seem to like media constantly moist but not soaked or dry and a higher comparative humidity. highland plants seem to want the rootzone moisture to swing between extremes. they also like a lower humidity overall. while further dryouts will increase resin content, but that is counterproductive if the dryness is detrimental to primary growth. secondary metabolites eventually run counter to plant health since they are designed to combat biotic dangers.

ive never used hempy but runoff readings for ec and ph are great ways to determine where a problem starts when compared to reservoir levels

I'm currently in earthboxes and check the ec/ph regularly. The plants once rooted in can drastically change the reservoir ec/ph overnight. They will show what they want. Very valuable measurement.

 

[Douglas.Curtis]

The most fragile terpenes begin vaporizing off at 70F, so I work to keep my temps below that. The only way to keep transpiration at max is to keep RH bottomed out in the high 20's to low 30's. Yes, I know this is right side up from what is normally preached.



The insane resin and terps is such a treat.

Should I expect stomatal closure issues this way? I moved from HID to LED while I switched from hydro to soil. Now I'm working with rabbit urine/manure and a whole new experience. Stuck trying to figure out what is base nutrient related, let alone transpiration/Ca related ones.

Truly appreciate the discussion here everyone, ty so much.

 

[Three Berries]

I use a liquid calcium chloride. It definitely solved the led yellowing at the tops an slow stunted growth. I apply it on top with a 1200 ppm mix, 1/4 cup or so when it starts yellowing and also one a week as a foliar spray at 2 tbs a gallon along with a light nute and a touch of some glycerin to keep the foliar spray liquid instead of drying out on the leaf.

Also have some Magnesium Chloride, it's a solid though and you don't need much. Both the chlorides are immediately available to the plant.

It's what they spray on the roads around here before a freeing rain or snow too FWIW. Keeps the water from freezing and no corrosion from salt.

https://bonide.com/product/rot-stop-...set-spray-rtu/

 

[Piff_cat]

The most fragile terpenes begin vaporizing off at 70F, so I work to keep my temps below that. The only way to keep transpiration at max is to keep RH bottomed out in the high 20's to low 30's. Yes, I know this is right side up from what is normally preached.

filedata/fetch?id=18106163&d=1648000014
filedata/fetch?id=18106164&d=1648000047
The insane resin and terps is such a treat.

Should I expect stomatal closure issues this way? I moved from HID to LED while I switched from hydro to soil. Now I'm working with rabbit urine/manure and a whole new experience. Stuck trying to figure out what is base nutrient related, let alone transpiration/Ca related ones.

Truly appreciate the discussion here everyone, ty so much.

the nice thing about vpd is that its based ona ratio and not absolute values. so each temperature will have a corresponding humidity level which ensures the correct amount of pressure to keep stomata at optimal levels. for this reason 30 rh at 70 is probly pretty close to right. further more the lower temperature will make stomata closure less likely due to lower transpiration loss. however as you recognize lower temps will effect transpiration levels. i had a real hard time going from hps to led because of the extreme infrared heat difference which severely decreased my transpiration rate. i actually had to add a waterproof heater. growing up on hps i never even thought about low ir because the battle is to reduce ir with hps. same thing with humidity the hps caused high transpiration so i needed to remove water vapor whereas the led slowed it down necessitating a humidifier. more things can go wrong environment stress wise with hps and more things go wrong with nutrients in led just my opinion

 

[f-e]

While lower transpiration rates call for Ca adjustment, another angle on this problem is combating closure. Potassium and chlorides both play a role in stopping the guard cells loosing their rigidity and the opening closing.

This run, I'm watching the increase in water consumption as the first hairs show. I feel certain the hairs loose moisture which isn't a process involving the stomata. As the hairs have shown, consumption has doubled, and my Ca input has been halved with no ill effect. No surprise there to be honest, but I had to see it.
There is a problem here, that leaves don't have hairs. The forming buds may desire less Ca in the feed, but the leaves won't. As yet no issue, but I suspect the leaves stores are being depleted. It's early days yet.

I'm using calcium chloride I think (canna mono) as chlorides drought resistance qualities are quite well known. I will mix my own soon. It's very cheap and gaining a lot of popularity. 50% increase in use by professionals in 2021 surveys iirc

 

[Douglas.Curtis]

I have very high transpiration rates. I've been absolutely LOVING the switch from HID to LED, sooo much easier without all the heat. lol

Oh, and I double checked my RH, it's been at 20% not 30%. Oops

I generally foliar once or twice during stretch with water soluble calcium(KNF). The leaves def absorb the calcium and no flowers to speak of yet.

Too much calcium in flower makes for puffy leaves from enlarged plant cells. The good stuff forms within the trichomes, never inside the plant. The extra plant matter only adds to the burnt plant flavor of the smoke.

Calcium chloride, eh? What does the chlorine add to terp and cannabinoid enzymatic pathways?

 

[f-e]

I can't imagine chlorine adds anything to the terp count. It should be reduced. It's cleaning action reduces plant stress. In some difficult areas, it's been seen as the mechanism increasing yields. Healthier plants, with resistance to fusarium being on the list. It should help with those moldy buds.

A few years ago chlorides were being avoided. Feeds formulated with non at all were thought good products. They would state it on the packaging. Now it's use is increasing a lot. The upper limit varies wildly across plant species. I guess proper grow op's have led to proper analysis for us.

 

[Douglas.Curtis]

Ok, thanks. I'll remember that when I have bad conditions?

KNF water soluble calcium is as easy as soaking toasted and crushed egg shells in vinegar. 1 part egg shell to 11 parts 3% distilled vinegar. Add time till no more bubbles when stirred. pH to 7 if necessary and use at 1 thousand to 1 for foliar.

 

[Three Berries]

Ok, thanks. I'll remember that when I have bad conditions? KNF water soluble calcium is as easy as soaking toasted and crushed egg shells in vinegar. 1 part egg shell to 11 parts 3% distilled vinegar. Add time, pH to 7 if necessary and use at 1 thousand to 1 for foliar.

I've used Calcium acetate before. Similar to the chloride as it is water soluble and immediately available. Good too if you have carbonates in the mix somewhere.

 

[Three Berries]

With my well water having a high Ca value I went back to it to mix my Miracle Grow nutes. The pH comes out almost perfect starting with 7.6 and ending around 6.5 when all is added. 400ppm Ca/Mg 93/7 is the well water. A little iron too.

Been suing rain water for the last couple years and nothing but problems because I neglected Ca.....

 

[VenerableHippie]

heres an article for ya. calcium is highly avilable in foliar. kelp contains tons of micronutrients hromones and just general goodness for the ladies. a 2 to 1 humic acid mixture greatly improves the action. now it is best absorbed by stomata underneath leaves but recent research has verified it also absorbed thru cuticle. when i grew in coco i had constant calcium magnesium problems due to cation exchange. calcium foliar is a miracle worker. altho i switched to rockwool i still use the foliar. cant go wrong
https://www.grozine.com/2014/07/16/f...cium-chloride/

I 'm in soil: Foliar N13.7, Ca 15.3, Mg 2.3, B 0.26 complexed with fulvic acid and mannitol derived from kelp each alternate week with foliar 10N 10P 10K foliar other week until late flowering.

 

[Piff_cat]

i like this chart easy to read. obviously 20 percent is very low desert style. but imo the best environment is the one gives you results ya like so do you if its goin well. also important to remember its leaf surface temp not ambient to measure. it does make a difference

https://www.dimluxlighting.com/knowledge/blog/vapor-pressure-deficit-the-ultimate-guide-to-vpd/

 

[Three Berries]

The AC Infinity fans with the Bluetooth Controller 67 will display the current temp, humidity and VPD. You can target temp or humidity but not the VDP. And it has a app.

During the winter here I use a small heater at first when the lights come on to boost the temp up to where it will stay on it's own from the lights. But you have to let it heat up then turn on the humidity control, I limit it to 80% during this time. Takes about an hour with room temps around 65F and tent temps stabilizing at 75F. Then target the VPD. The humidity will rise up into the 70% range.

It also has a humidity offset that will increase the fan speed 1 point (0-10) per 1 % rise if you want. This is good if you get big or rapid swings in humidity. And it has a leaf temp offset too you can pick at 2F. If you get one consider the next size up that what you think you need. It will be quieter.

The fan seldom runs at more that 3 out of 10. But it you are pushing it a long way or though many bends or a filter the bigger size will be appreciated.

In the small tent I'm also experimenting with a small piezo electric dehumidifier when the lights are off. It's 40 watts and keeps it under 70% but not anywhere near the ideal VDP when the lights are off.

 

[Piff_cat]

yea i have an ac infinity product fan as well. i like them although the interface could be easier. the cool thing about that vpd page is theres a calculator function which allows you to change the ambient/leaf surface temp offset. with range from 0 to 5 degrees between the leaf and the air those leaf temps make a significant difference in your target humidity. but you do need one of those gun temperature meters like used for bho etc. dimlux has lots of good info

 

[ButterflyEffect]

the way i look at humidity is a shield. it allows you to run the temp you want high enough so that transpiration is peak and stomata is open to ideal amount. lowering that shield increases transpiration at first but once it crosses over to the dark side the stomatas close as an emergency intervention to slow water escaping.in turn stops calcium from being mobile but also can lockout other nutrients due to cascade effect on taking up too much too fast. thats where leaf surface temp really comes into play. similar to chuggin a milkshake leads to stomac ache.

its hedgin your bets compared to how often your able to refresh roots with feed. so there are inhibitive dangerous zones at too dry or too moist and then a sweet spot zone which you can choose either aggressive(less) or safe(high) rh levels. it is also strain dependent to a point. lowland plants seem to like media constantly moist but not soaked or dry and a higher comparative humidity. highland plants seem to want the rootzone moisture to swing between extremes. they also like a lower humidity overall. while further dryouts will increase resin content, but that is counterproductive if the dryness is detrimental to primary growth. secondary metabolites eventually run counter to plant health since they are designed to combat biotic dangers.

ive never used hempy but runoff readings for ec and ph are great ways to determine where a problem starts when compared to reservoir levels

Thanks. That's a very helpful explanation. As for hempy runoff readings, it's complicated it seems. For one, the pH always reads a good point higher than the input. Always. I've been told to ignore it. The salts do tend to build up, which is why I'm cutting the amount of vermiculite down, as it has a high CEC compared to the perlite. Hopefully, I can get the rootzone in better shape.

 

[ButterflyEffect]

The most fragile terpenes begin vaporizing off at 70F, so I work to keep my temps below that. The only way to keep transpiration at max is to keep RH bottomed out in the high 20's to low 30's. Yes, I know this is right side up from what is normally preached.

filedata/fetch?id=18106163&d=1648000014
filedata/fetch?id=18106164&d=1648000047
The insane resin and terps is such a treat.

Should I expect stomatal closure issues this way? I moved from HID to LED while I switched from hydro to soil. Now I'm working with rabbit urine/manure and a whole new experience. Stuck trying to figure out what is base nutrient related, let alone transpiration/Ca related ones.

Truly appreciate the discussion here everyone, ty so much.

I've followed many of your posts so I know that you're a big fan of low temps and very low humidity. I'm not qualified to speak to the better method, but I can certainly see how one way prioritizes quality over quantity. Unfortunately in my case, I can't get my numbers down much more. Perhaps one day when I can afford to move my 3rd room to LED, I can start testing these theories myself.

As always, thank you for the valuable input.

 

[ButterflyEffect]

I use a liquid calcium chloride. It definitely solved the led yellowing at the tops an slow stunted growth. I apply it on top with a 1200 ppm mix, 1/4 cup or so when it starts yellowing and also one a week as a foliar spray at 2 tbs a gallon along with a light nute and a touch of some glycerin to keep the foliar spray liquid instead of drying out on the leaf.

Also have some Magnesium Chloride, it's a solid though and you don't need much. Both the chlorides are immediately available to the plant.

It's what they spray on the roads around here before a freeing rain or snow too FWIW. Keeps the water from freezing and no corrosion from salt.

https://bonide.com/product/rot-stop-...set-spray-rtu/

Ok. Nice! You're the second person to recommend the chloride. I will be picking some up in the very near future. Thank you very much for the advice!

 

[ButterflyEffect]

the nice thing about vpd is that its based ona ratio and not absolute values. so each temperature will have a corresponding humidity level which ensures the correct amount of pressure to keep stomata at optimal levels. for this reason 30 rh at 70 is probly pretty close to right. further more the lower temperature will make stomata closure less likely due to lower transpiration loss. however as you recognize lower temps will effect transpiration levels. i had a real hard time going from hps to led because of the extreme infrared heat difference which severely decreased my transpiration rate. i actually had to add a waterproof heater. growing up on hps i never even thought about low ir because the battle is to reduce ir with hps. same thing with humidity the hps caused high transpiration so i needed to remove water vapor whereas the led slowed it down necessitating a humidifier. more things can go wrong environment stress wise with hps and more things go wrong with nutrients in led just my opinion

This right here is why I;m struggling with the justification to go LED. I'm using CMHs, so to get to the same PPFD, the LEDs would use close to the same energy. I'd be likely using less A/C, but a heater is 1500W compared to around 600 for the A/C. Then you have the price for admission, and that'd be close to $1000 per room. Yikes!

I depend on my 3 rooms always producing so that would be a critical error to make at this time. If I get to a point with excess stock that I can retrofit my 3rd room, I'll certainly consider it.

 

[ButterflyEffect]

While lower transpiration rates call for Ca adjustment, another angle on this problem is combating closure. Potassium and chlorides both play a role in stopping the guard cells loosing their rigidity and the opening closing.

This run, I'm watching the increase in water consumption as the first hairs show. I feel certain the hairs loose moisture which isn't a process involving the stomata. As the hairs have shown, consumption has doubled, and my Ca input has been halved with no ill effect. No surprise there to be honest, but I had to see it.
There is a problem here, that leaves don't have hairs. The forming buds may desire less Ca in the feed, but the leaves won't. As yet no issue, but I suspect the leaves stores are being depleted. It's early days yet.

I'm using calcium chloride I think (canna mono) as chlorides drought resistance qualities are quite well known. I will mix my own soon. It's very cheap and gaining a lot of popularity. 50% increase in use by professionals in 2021 surveys iirc

So you use the chloride in your base, or as a foliar?

 

[ButterflyEffect]

With my well water having a high Ca value I went back to it to mix my Miracle Grow nutes. The pH comes out almost perfect starting with 7.6 and ending around 6.5 when all is added. 400ppm Ca/Mg 93/7 is the well water. A little iron too.

Been suing rain water for the last couple years and nothing but problems because I neglected Ca.....

I could write a book about the issues I;ve had with rain water. Lately, I've started adding 20-25% of my collection tanks volume with well water. This gets the Ca up and buffers the water. Now I'm using nothing but Jacks A & B and a little AgSil and nothing else. No extra Mg, either.