Question regarding Ca uptake in early flower and VPD

[f-e]

A few studies of nutrient accumulation in plant tissue, have led to the idea that Ca and Mg are needed most in the latter half of flower. There is a chart of this often posted from an additives supplier. Aptus I think.
My own studies of the runoff show they are right about Mg. Other studies have found half the Ca is already in the plant at that point though. Methods of increasing Ca early are coming forth, and a look at peoples grows see's most LED growers are not raising the Ca in the latter half of bloom. Guided by results, they are more likely to drop the Ca and increase Mg.

I look at the idea of lowering Ca in favour of Mg as well based. I too see the same Mg like signs on one strain that come late, and are quite tied to high EC also. So I need more Mg but also there is something antagonising it. Well.. there always is, but it's more the problem than an actual lack of Mg. Calcium and K are the only likely culprits.

I see strong visual evidence that Ca needs lowering, along with a mild raise in Mg. Some time into the latter half of bloom. 25 days is early, but then a lot of Ca has been added.

 

[jackspratt61]

Based on tissue testing some have found that after stretch the ca in the plant changes little with normal ratios of k/ca. The time for maximum ca uptake has passed. Adding a bit of extra B at flip with Ca is a good practice. .0050x total ppm ca=total B is the same rate jacks clone formula uses to initiate rooting which is what's happening at flip. New roots to support upcoming flowering.

 

[Three Berries]

As I expected with the heavy Ca and 1.5x nutes some nute burn is starting to show up on a lot of the serrated edges, not just the top. So time for a flush.

My test run dummy at 4 weeks flower. Been getting the heavy CaCl2 top dress treatment for over 6 weeks. Always waited until it showed the yellow new tips though.

GDP in FoxFarm Happy Frog using Miracle Grow veg and flower nutes in well water with langbeinite in the soil and CaCl2 poured on top. This is the worst looking of the four I have going now.

 

[Piff_cat]

What's causing the dark green leaves with white midrib,red petioles on older leaves and pooling of dark green at leaf tips?

low rootzone temp may be limiting phosphorous or possibly water temp but dark green usually phosphorous

 

[f-e]

low rootzone temp may be limiting phosphorous or possibly water temp but dark green usually phosphorous

Interesting thoughts. I'm using a basic feed, in line with others on the shelf. With little changed except for extra Ca. Which aids P intake. Perhaps that's leaving me a bit short of P.
The red is quite old, but the pooling more recent. I dropped the food 20% and they did a reach for the sky. Perhaps linked to a root expansion, or it was a bit toxic. Hard to say. They get a fair bit of Nitric Acid. Enough to make a contribution around 10% more N.

I have just been dunking this tray for weeks. No effort to run anything through them. Some issues are to be expected. More issues TBH. I posted them as I'm surprised they have remained reasonable. The root zone must be really quite high. I bet I see an issue when I pot up.

 

[ButterflyEffect]

My oldest flowering plant, the test girl now at 25 days into 12/12, on my last application of CaCl2 didn't improve. But the telltale sign wasn't yellow tips on new growth but rather yellowing of the not so new top leaves between the veins. I was expecting a change and anticipating switching to MgCl2.

This yellowing went away with the Mg and or nutes.

So it got some full strength nutes with 2gr Epsom per gallon and a top dressing of ~125ml MgCl2 600 ppm. Responded great. Did the last major defoliate today.

The four I had the transplant issues with responded remarkably well to the CaCl. I needed to nudge them with Mg first, as that was also showing, but the yellowing up top started to diminish in about 3 days.

 

[Three Berries]

I've quit with the CaCl2 for now as I was doing. I flushed everything and an now on straight well water. I'll go though a couple waterings with that then see how they all look. Both flower plants have slight burnt edges on most of the leaves so they got too hot.

One thing I've found out with the Ca++ when it is freed from the hard water carbonate, such as when the fertilizer is initially added to hard water and the pH lowers or if you add a form that is totally soluble in water like Calcium Chloride or Calcium Acetate, if you add epsom salt to the mix it takes out the Ca++ and it settles on the bottom due to the sulfate reaction.

I let the pH get too low in the pots. Didn't water to runoff enough. I've got some 1" spacer rings I put between the pot and saucer so it's easier to get the run off and let it evaporate for humidity if needed. But wasn't using them. Did finally get some good heavy large saucers though. Flat surface so you can suck up most of the extra with a baster if you want.

 

[f-e]

The best thing I have done lately is add saucers. I used 8 5" pots in a meter, so that's 8L of Terra per meter. Half of usual, but with a saucer. My aim was to give a similar water amount, but much better access to it while it was there. The saucer offering an extended 'very wet' period. Then the smaller pots a quick dry back to ensure I wasn't sodden. Many of my difficulties lay with the fact I'm in small pots. So I just don't get that long a time in a soaking wet state. My bigger builds have no issues where they have a res below them. Just this micro-grow.

I'm really focused in on the idea of reducing Ca after stretch now. I have trialed it a couple of times. If I don't reduce it, my run-off will rise on the same day each time. Over the cource of 3 days, I could have my runoff go from 15% above what was fed, to 50% above. I have this pretty much pinned down to Ca no longer being taken up. A week or so later my roots won't be pearly white any more. I need some feedback on that timing of root colour change from other growers. Just maybe an older root system is less capable of drinking with high Ca. High Ca is known to reduce Ca intake as it's like a thickening agent. So an aging root system ties a few things together. Where uptake is limited by high Ca and a less capable root.

Lowering Ca after stretch meant I didn't reach the usual runoff figures, though I used twice as much food (still only the bottle dosage)
Final figures are not in, but there is nothing to chuck away, and no gaps. Just nugs. No heads over about 200mm long, but they must be 60mm wide. We will see..



Veg plants got 4ml feed not 5ml, and went N deficient. Potted up now, so that phase is over. Pooling unsolved, but stopped.

 

[G.O. Joe]

Just maybe an older root system is less capable of drinking with high Ca.

There is some scientific work saying that in at least some plants Ca is only absorbed by new growth roots. I see root tips turn brown after 45-60 days in flower and prefer not to go past that. Runoff ppm might get complicated if the plants eat organics without EC and release inorganics with EC to balance the charge.

 

[Piff_cat]

thing is that when your growing for secondary metabolites limiting factors are more important. vpd, higher co2, higher temps etc only matter to the point where one ingredient reaches a wall. calcium being immobile and essential for new growth is a prime candidate to be a limiting factor. it is pretty hard to give too much calcium in foliar and the upside is huge. when i started running a simple kelp, humic acid, dolomite lime foliar my plants quality and yield exploded. its like having a porsche but your tranny only has 2 gears. can only go so fast without 3 4 5 6. nutrients vs biostimulants (whey protein, hormones, chitin aminos etc)

 

[exploziv]

Isn't dolomite lime so poorly soluble in water that we can call it almost insoluble? I would say that isn't the stuff that helps your plant, if I had to pick out of that list!

 

[f-e]

Feed is what a plant can't live without/Insert another wise line here.




My pH up is a brown staining seaweed. Maxicrop by Seaward. I don't really get to keep white roots, because of it. I should really be talking about root tips, but it's surface stuff I'm looking at. Long ago I used gutters, which is my last real experience of root watching. The root system would usually expand until about week 3 or 4. In line with stretch. Then a few weeks on it would get shabby. When you might get another 2 weeks out of it.
Always some more work to do, but I'm getting there.


Seaweed and Fulvic show mutual support in testing. IIRC a 1:10 ratio respectively. More wouldn't be wasted, but offered no gain to the other. I pitch them together after reading the study. There is usually a good couple of days that follow, but it doesn't seem repeatable for a while. Perhaps it's shock therapy. It does something though. Might not be vital feed components, but undeniably useful.
Another study say no Fulvic late in flower. The reason escapes me. It's 8am and I'm still on it.

 

[Growenhaft]

Lime makes rich farmers and impoverished heirs.

calcium is essential for the development of biomass... but if large biomass is no longer produced, too much calcium disrupts the uptake of nutrients and damages the medium. the only nutrient whose need is constantly increasing is... potassium. Potassium is responsible for the entire gas exchange and water balance of the plant. the older the plant as a whole, the more difficult it is for gas and water exchange... due to the aging of the leaves and stems. despite this, the plant with a constant increase in turgor. this requires more potassium and boron. if you increase potassium you always have to increase magnesium as well... because this would be worse absorbed by a higher potassium.

i only increase calcium during the transition from growth to flowering... and then go back to my starting level. luckily for me this can be regulated pretty well with my tap water... during the stretches i use my extremely hard water without mixing it with rainwater. means... the ec value of the starting water before adding the fertilizer is 0.67 during the stretch... before and after the stretch it is a target of 0.45 due to the addition of filtered rainwater.

I regulate the increase in potassium and boron by a targeted increase in all nutrients... because that's the only way everything stays in the right proportions... which in turn is more important because otherwise nothing is gained. towards the end of flowering...starting from week 7...i reduce the nutrients significantly...go back to an ec of 1.5...at the same time i adjust my ph in the coco to 5.3 ... and try to keep him there. because in this range, potassium, boron and magnesium are absorbed particularly well... if the medium is not permanently too moist... but is rather kept a little too dry.

 

[Three Berries]

Isn't dolomite lime so poorly soluble in water that we can call it almost insoluble? I would say that isn't the stuff that helps your plant, if I had to pick out of that list!

It's a carbonate that will be reduced to CO2 and Ca/Mg with low pH. Also a buffer that will, until consumed and in enough quantity, keep the pH at it's native level, or with limestone ~7-8.

Like anything else if given in excess it interferes with the pH level.

I'm just guess but if the runoff pH is in the 5.5-6.0 range Ca/Mg buildup is not an issue. If no runoff then it probably is as is pH of the media.

 

[Three Berries]

FWIW pH up is usually a potassium carbonate or potassium hydroxide type product. I use food grade bicarbonate and it will raise the pH about .1 per teaspoon into a +6.0 mix. Takes over night to fully stabilize. You can see the CO2 bubbles coming off as it decomposes.

But I was using KOH, Potassium Hydroxide, and it will strip the Ca right out of the nute mix immediately.

 

[Piff_cat]

Lime makes rich farmers and impoverished heirs.

calcium is essential for the development of biomass... but if large biomass is no longer produced, too much calcium disrupts the uptake of nutrients and damages the medium. the only nutrient whose need is constantly increasing is... potassium. Potassium is responsible for the entire gas exchange and water balance of the plant. the older the plant as a whole, the more difficult it is for gas and water exchange... due to the aging of the leaves and stems. despite this, the plant with a constant increase in turgor. this requires more potassium and boron. if you increase potassium you always have to increase magnesium as well... because this would be worse absorbed by a higher potassium.

i only increase calcium during the transition from growth to flowering... and then go back to my starting level. luckily for me this can be regulated pretty well with my tap water... during the stretches i use my extremely hard water without mixing it with rainwater. means... the ec value of the starting water before adding the fertilizer is 0.67 during the stretch... before and after the stretch it is a target of 0.45 due to the addition of filtered rainwater.

I regulate the increase in potassium and boron by a targeted increase in all nutrients... because that's the only way everything stays in the right proportions... which in turn is more important because otherwise nothing is gained. towards the end of flowering...starting from week 7...i reduce the nutrients significantly...go back to an ec of 1.5...at the same time i adjust my ph in the coco to 5.3 ... and try to keep him there. because in this range, potassium, boron and magnesium are absorbed particularly well... if the medium is not permanently too moist... but is rather kept a little too dry.

this very good advice potassiums importance isnt stressed enough when growing in coco mag and potassium constant nightmare due to cat ion relationship. build up salt or over leech potassium begins a vicious cycle. in case i didnt mention, the dolomite lime is applied as a foliar along with the kelp and humic. obviously gets toned down when bud build up gets larger. manipulating the turgor and feeding regiment nighttime humidity/temp in order to get full calcium dispersion at top of plant can be tough especially if different strains/sizes are in rooms. foliar cuts thru the issues of calcium immobility and stops it from becoming a limiting factor. in fact there are now nano drilled calcium carbonate products small enough to enter the stomata at which point they are in essentially the same form co2 turns into in stomata. referred to as foliar co2, but there is also a process to infuse the gas into foliar as well, but calicum gives you both advantages.

 

[Three Berries]

Calcium Chloride and Magnesium Chloride work great as a foliar spray. And in fairly high concentrations if needed, +1000ppm.

 

[obione]

That's the chart I've been going by. I've been trying to incorporate the formulas into my controllers' code, but I gave up. I have different 4 different programs that I run during flower and it's close enough that trying to get the numbers tighter would be a diminishing returns situation.

Basically, it's Stretch(80F/70H), Mid-Flower(80F60H), Early Ripen(78F/50H), Late Ripen(76F/40H)

Hi guys, interesting read, appreciated. I had a pretty good hydro set up, with hids dehumdifier, ac, extraction and all the basics you need, no CO2 tho. And while playing with the temp, humidity, extraction, feeds i got to the point where i was getting realy good yeald. Temp at 1st week of flower starts at 76-77, RH 60%. Each week droped a degree from temp down to 70. Same with humidity, starts at 60% droping 5%per week. Strong extraction prooved to be key too, as you all know that.

 

[Douglas.Curtis]

Hi guys, interesting read, appreciated. I had a pretty good hydro set up, with hids dehumdifier, ac, extraction and all the basics you need, no CO2 tho. And while playing with the temp, humidity, extraction, feeds i got to the point where i was getting realy good yeald. Temp at 1st week of flower starts at 76-77, RH 60%. Each week dropped a degree from temp down to 70. Same with humidity, starts at 60% dropping 5%per week. Strong extraction proved to be key too, as you all know that.

Thank you for this...
So I read this and my first thought goes to stems (Don't ask me, I just live with this brain. lol)
One of my goals is to have a single central stem in each flower, with little to no branching at all within the flower itself. You can gently crush the flower, and then remove the single stem from the frosty pile of bits. If there is any 'branching' going on with the main stem it is only short nubs.

Do your flowers have multiple stems within each flower, more of a tree looking structure than a knotty fence post? I would think there would be much more 'branch' than just nubs, yes?