The Cal-Mag of my dreams?

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Steve Johnson
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The Cal-Mag of my dreams?

Post by Steve Johnson »

I think so, and the following is for those of you who'd like to up your fertilizer game...

Just to set the table for this little presentation, I grow the vast majority of my cacti in a 60% pumice/40% granite gravel mix -- essentially a hydroponic approach, so I have to fertilize every time I water. My fert of choice is Dyna-Gro All-Pro 7-7-7. The soil-less mix and 7-7-7 have been a winning combination ever since I got away from a soil-based mix in 2012. Here is the All-Pro's chemical analysis:

Image

Recommended dilution for cacti and succulents is 1/2 tsp. per gallon of water. Here in the US, P is reported as P2O5, and K is reported as K2O. However, the Oxygen in P2O5 and K2O has no nutrient value, so the true elemental NPK available to our plants is 7-3.052-5.81. Since P should be lower than N, that's a good balance, but K should be about 1.5 times higher than N. Without getting into the technical details, I'll just mention that I add the right amount of Potassium sulfate when I whip up a gallon of watering solution, and the improvements with higher K have been amazing. Calcium and Magnesium are important minor nutrients, so the 2% Ca and 0.5% Mg in the 7-7-7 is not only a good balance, it's also a pretty good amount. However, as MikeInOz said in several posts elsewhere, there's no such thing as too much calcium. That being the case, I decided to up my fert game with the addition of a Cal-Mag supplement starting in June. And here's what I selected:

16oz_CMOAC_Shadow_540x.jpg
16oz_CMOAC_Shadow_540x.jpg (14.43 KiB) Viewed 4984 times
A few FAQs from the TPS website (https://tpsnutrients.com/products/calmag-oac):
  • What is CalMag OAC made out of?
    We start with a highly pure and organic source of magnesium and calcium. We then micro-chelate it with organic acids and a plant extract package. The result is the most bioavailable CalMag in the gardening and hydroponic industry. One example of this is that when this CalMag is used in soil it is 10+ times more effective at uptake than nitrate calmags.
  • Is there Iron in CalMag OAC?
    Yes there is iron, as well as an array of other micros. The NPK is 0-0-0 and the mineral breakdown is as follows: Nitrogen: 0% Calcium: 4.5% Magnesium: 1.1% Boron: 0.005% Copper: 0.007% Iron: 0.01% Manganese: 0.01% Sulfur: 0.05% Zinc: 0.01%
  • Does CalMag OAC need to be shaken before use?
    A shake before use is a great idea, though not required. The amino acids from the plant extracts in CalMag OAC can bind up over time. If you give it a shake they should reintegrate into the solution. If you mix feed water with the aminos stuck together, it's not a problem. The vigor of watering and mixing your feed water will disperse the aminos again.
  • What is the shelf life of CalMag OAC?
    CalMag OAC is guaranteed for 18 months from date of purchase, though it doesn't really expire. We recommend shaking up older bottles before use to mix the amino acids back into solution.
TPS recommends a dilution of 1-2 ml. per gallon, so 1/4 tsp. (a touch over 1 ml.) per gallon is just about right, and it doubles the amount of Ca and Mg provided by the 7-7-7 alone. This brings up an interesting point -- "when this CalMag is used in soil it is 10+ times more effective at uptake than nitrate calmags." If the Ca and Mg in the 7-7-7 rates as a nitrate CalMag, could it be that my cacti are actually taking up more Ca and Mg from the TPS fert than they are from the 7-7-7? If so, they'll be getting "more bang for the buck" -- sweet! And I have a feeling that the additional micronutrient boost should be helpful.

If you'd like to try the TPS CalMag, there are a couple of things you'll need to be aware of:
  • When you prepare your watering solution, your primary fert of choice should go in first and the TPS fert supplement should go in last. Be sure to shake your watering solution thoroughly before you water.
  • You'll need to water your plants right away. Unfortunately the TPS product precipitates out if you let leftover watering solution sit in the container for more than a few hours, and there's no way to get it back in solution.
The collection has received only a couple of waterings with the TPS fert supplement, so it's too early to tell if I see any improvements beyond what I already see with almost 2 years of higher Potassium in the fert regimen. We'll find out by the end of summer. I'm way, way, way overdue for an end-of-summer review on my Member Topics thread, so that would be a good opportunity to post a whole bunch of "before and after" photos as we assess the results.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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zpeckler
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Re: The Cal-Mag of my dreams?

Post by zpeckler »

Thanks for your guidance through the world of fertilizer, Steve! This growing season I've followed your DynaGro + potassium regimen and I'm definitely seeing a difference. Already ordered a bottle of this calmag.
--------------------
Zac

Butte County, CA, USA
USDA Zone 9b
Mediterranean climate; hot, dry, sunny summers with rainy, moist, mild winters.
OWgave
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Re: The Cal-Mag of my dreams?

Post by OWgave »

Hello Steve-

Was just wondering if you thought of the “end of the summer review” of the TPS Cal-Mag on your collection?

Would love to know if I should add it to watering regiment.

Good Growing,
OWgave
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Steve Johnson
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Re: The Cal-Mag of my dreams?

Post by Steve Johnson »

OWgave wrote: Sun Sep 25, 2022 1:42 am Hello Steve-

Was just wondering if you thought of the “end of the summer review” of the TPS Cal-Mag on your collection?

Would love to know if I should add it to watering regiment.

Good Growing,
OWgave
Yes, and when I get the 2022 review going, I'll describe the improvements I've seen since I upped my fertilizer game last year (Potassium sulfate to supplement my Dyna-Gro 7-7-7 watering solution) and this year (TPS Cal-Mag to go with the 7-7-7 and Potassium sulfate). Of course I still need to do a big cactus-by-cactus photo shoot before the SoCal growing season ends, so I have that on tap for next weekend. Then it'll be a matter of assembling before-and-after photos -- that's the easy (albeit time-consuming) part. The hard part is putting the words and pictures together since I want my reviews to be both entertaining and educational for our members. I do it on the "installment plan", so I'll post each installment as soon as it's ready for prime time on the forum.
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
OWgave
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Re: The Cal-Mag of my dreams?

Post by OWgave »

Great, looking forward to your results.

You, Mr. Jerry, Mr. Iann and the greenknight are my guru’s when it comes to fertilizer questions for my agaves which I greatly appreciate.

Good Growing,
OWgave.
Last edited by OWgave on Sun Sep 25, 2022 1:10 pm, edited 1 time in total.
DaveW
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Re: The Cal-Mag of my dreams?

Post by DaveW »

In the UK I tend to use Tomorite tomato feed most of the year = NPK 4-3-8 since the ratio is the same as 8-6-16 if doubled up since its just dependent on the strength of dilution of the liquid in water, therefore similar to Steve's 7-7-7 plus extra potash? I will also often use a normal fertiliser when the plants are starting to grow early in the year.

"Tomorite is often recommended because it is a high potash feed, which concentrates its efforts on promoting fruit & flower growth. It does also contain a percentage of nitrogen and phosphorus + important trace elements.

Remember all fertilizers consist of three basic elements:

N - Nitrogen = leaf growth

P - Phosphorus = root growth.

K - Potash = fruit & flower growth

A typical 'balanced' fertilizer will contain an equal measure of all three elements.......one such being *'Growmore', which has a NPK reading of 7-7-7.

*National Growmore' (as it was once called) was formulated by the UK government during WW2 as part of the country's 'Dig for Victory' campaign."


As Steve points out if you are going to use a neutral substrate = a mineral mix, which is virtually growing using hydroponics, you need a fertiliser that provides all the trace elements some general fertilisers often assume will be provided by organic soils. There are special fertilisers sold for hydroponics with all the trace elements needed. However, I don't know if you can buy trace element supplements to add to general fertilisers lacking them?

https://ibiologia.com/trace-elements-in ... nd-plants/
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jerrytheplater
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Re: The Cal-Mag of my dreams?

Post by jerrytheplater »

Dave, trace element fertilizer can be purchased on its own. In the Aquatic Plants hobby, one product used is called Nutritrace CSM which is made by a Canadian producer of fertilizer for the greenhouse industry. https://www.plantproducts.com/us/images ... -05-30.pdf I buy it in 25 lb bags and repackage it into one pound packs. It has fallen out of favor in the hobby though, and primarily due to an over application to boost iron which brought all of the others out of balance and introduced some toxicity. Another lesson in you have to be patient in the plant growing hobbies.

CSM stands for Chelated Special Minerals. In the US it does not contain Boron. In Canada it does.

I know there are other mixes. Millers Microplex is another.
Jerry Smith
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45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
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Mrs.Green
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Re: The Cal-Mag of my dreams?

Post by Mrs.Green »

DaveW wrote: Sun Sep 25, 2022 9:32 am In the UK I tend to use Tomorite tomato feed most of the year = NPK 4-3-8 since the ratio is the same as 8-6-16 if doubled up since its just dependent on the strength of dilution of the liquid in water, therefore similar to Steve's 7-7-7 plus extra potash? I will also often use a normal fertiliser when the plants are starting to grow early in the year.

This caught my attention. I hve never thought of checking tomato ferts but seeing this I did a search for available tomato ferts here and came up with this; https://www.hornum.com/produkter/hornum ... ng-1-liter ( scroll down for declaration) Could this be used for cacti?
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Re: The Cal-Mag of my dreams?

Post by jerrytheplater »

Before I answer if this fertilizer is suitable, what form is the Phosphorous and Potassium reported in? In the US, Nitrogen is reported as %N, Phosphorous is reported as %P2O5-NOT %P, and Potassium is reported as %K2O-NOT %K.

And, are you wanting to follow the recommendation of MikeinOz for fertilizing which Steve Johnson is promoting? It is possible to adjust almost any fertilizer to meet the nutrient ratio they promote.

As far as the trace elements in this Hornum fertilizer, they will work. I like how low the Boron is.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Steve Johnson
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Re: The Cal-Mag of my dreams?

Post by Steve Johnson »

I think the tomato fertilizer Mrs. Green mentioned is reporting elemental P and K. If that's the case, we'll break the 4.2% N, 1.4% P, and 7.0% K down into a ratio. Using N as a constant of 1, the NPK ratio is 1:0.33:1.67 -- good balance not just for tomatoes, but for cacti and succulents too. Only thing missing in the fert's chemical analysis is Calcium, although she can add a little bit of limestone or gypsum to her mix as a Calcium source. Unfortunately I have zero experience using either limestone or gypsum in a cactus mix, but I'm sure that other members can give her some guidance here.
If you just want photos without all the blather, please visit my Flickr gallery.
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Re: The Cal-Mag of my dreams?

Post by jerrytheplater »

I just did some searching and learned that fertilizer labels in Denmark list the Macro nutrients in elemental percentages. This means that the Hornum Tomato fertilizer with an actual concentration of 4.2%N-1.4%P-7.0%K is very close to the ratio MikeinOz and Steve Johnson are aiming for. That ratio, if exactly as Mike suggested, would be 4.2-1.68-6.3. The Hornum fertilizer is really good enough as it is without having to add any additional Macro nutrients. A little lower than ideal on P and a bit higher than ideal on K, but not enough to worry about.

But, it does not contain any Calcium at all. Beware of mixing Ca and P. Hornum label says it should be diluted 1 part concentrated fertilizer to 200 parts water. I did not calculate what concentration N that would give you. I aim for 25-50 ppm N in my water. Others are up to 100-200 ppm N. I'm sure you could email Hornum and ask them. I had to use Google Translate to read the website.

I'm going to have to stop there. Its late and I am leaving to drive up to New Hampshire tomorrow (5 hours). I most likely won't be back on the site here till I get back in about a week.

And I didn't see Steve's post before posting mine. We agree. Although limestone in the mix might react with the phosphate in the fertilizer. Might not be a bad idea to water with a dilute Calcium Nitrate from time to time, rather than limestone in the mix.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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Steve Johnson
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Re: The Cal-Mag of my dreams?

Post by Steve Johnson »

jerrytheplater wrote: Tue Sep 27, 2022 4:16 amMight not be a bad idea to water with a dilute Calcium Nitrate from time to time, rather than limestone in the mix.
Actually, that's an excellent idea because this controls the amount of Calcium going into the plants whenever they're fertilized -- better than guessing if one would have the right amount of limestone in the mix. As I learned from MikeInOz, the ideal Ca-to-Mg ratio is 4:1, and since the Hornum tomato fert contains .63% Mg, the target amount of elemental Ca in Calcium nitrate should be 2.52%. It'll simply be a matter of calculating the right amount going into the watering solution with Hornum fert added. Unfortunately my fertilizer math skills are limited to speaking in teaspoons and gallons, so I have no idea about what a European grower like Mrs. Green should do regarding proper mL-per-L dilution rates.

Edit: Unless I'm mistaken, Calcium nitrate adds Nitrogen to the N in the Hornum fert. That will upset the N-to-K balance Mrs. Green is aiming for, so Calcium citrate should be a more appropriate Calcium source.
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Re: The Cal-Mag of my dreams?

Post by jerrytheplater »

We didn't leave yet and I peeked! Never thought about Calcium Citrate. It is a great idea. But don't mix it with the Hornum fertilizer. Water on alternate days, or many hours apart. Plus, the Citrate will grow lots of bacteria, so don't mix up more than you need. I can do the calculations, just tell me what you have or can get. There is time as you are most likely not fertilizing any more this season.

Hopefully, Mrs. Green, the undersea gas pipeline fiasco will not be a problem for you and your cacti!!!!
Jerry Smith
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45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
elomeno
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Re: The Cal-Mag of my dreams?

Post by elomeno »

When you water, how much do you water?
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Re: The Cal-Mag of my dreams?

Post by jerrytheplater »

elomeno wrote: Wed Dec 07, 2022 6:09 am When you water, how much do you water?
The answer to this question has many factors behind it. Potting mix, outside temperature, season of the year, exposure, type of cactus or succulent being grown: jungle epiphytes or desert under full exposure or grassland shaded plants,...

What kind of potting mix? Mineral, no organic: water very frequently until the water comes out of the pot. Maybe 25% organic water less frequently, but still let the water flow out of the bottom of the pot. Don't let the pot stand in water.

Most, if not all cacti don't like water standing around the roots. You have to judge your own pots.

I'll let others add more to this answer.
Jerry Smith
Bloomingdale, NJ
45 inches (114 cm) rain equivalent per year, approx. evenly spread per month
2012 USDA Hardiness Zone 6b: -5F to OF (-20C to -18C) min.
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