Oroya peruviana and limestone stopping growth?

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Download
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Oroya peruviana and limestone stopping growth?

Post by Download »

I've got a bunch of O Peruviana depressa pups I pulled off my plant about 6 months back. I put them under my grow lights for the winter and in that time they've all gone from pinky sized to thumb sized and bigger.

I repotted them a few days ago. For my potting mix, I've recently started adding in seashell based chicken grit to improve drainage and increase the mineral content (it's hard to find very coarse sand for a good price where I am), but just now I noticed that Llifle says O Peruviana hates limestone which is mostly calcium carbonate, which is what seashells mostly are.

Anyone got any idea how true this is? I know Llifle can be wrong, so before I repot them all again, I was hoping to hear some other people's thoughts.
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Steve Johnson
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Re: Oroya peruviana and limestone stopping growth?

Post by Steve Johnson »

Download wrote: Mon Sep 13, 2021 4:41 am I've got a bunch of O Peruviana depressa pups I pulled off my plant about 6 months back. I put them under my grow lights for the winter and in that time they've all gone from pinky sized to thumb sized and bigger.

I repotted them a few days ago. For my potting mix, I've recently started adding in seashell based chicken grit to improve drainage and increase the mineral content (it's hard to find very coarse sand for a good price where I am), but just now I noticed that Llifle says O Peruviana hates limestone which is mostly calcium carbonate, which is what seashells mostly are.

Anyone got any idea how true this is? I know Llifle can be wrong, so before I repot them all again, I was hoping to hear some other people's thoughts.
I used to fall for the myth that limestone is a natural growth inhibitor. With that said, Calcium needs to be balanced with Magnesium. I get both through the Dyna Gro All Pro 7-7-7 I've been using since 2012, Ca-to-Mg ratio is 4:1 -- pretty much ideal for cacti. IMO O. peruviana should do well with a good Ca-Mg balance, so I wonder if the idea that the species "hates" limestone comes from growers who don't appreciate the importance of Mg in this equation. MikeInOz knows a lot more about it, so hopefully he can give you more properly targeted advice on the matter.
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Download
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Re: Oroya peruviana and limestone stopping growth?

Post by Download »

Steve Johnson wrote: Mon Sep 13, 2021 5:49 am
Download wrote: Mon Sep 13, 2021 4:41 am I've got a bunch of O Peruviana depressa pups I pulled off my plant about 6 months back. I put them under my grow lights for the winter and in that time they've all gone from pinky sized to thumb sized and bigger.

I repotted them a few days ago. For my potting mix, I've recently started adding in seashell based chicken grit to improve drainage and increase the mineral content (it's hard to find very coarse sand for a good price where I am), but just now I noticed that Llifle says O Peruviana hates limestone which is mostly calcium carbonate, which is what seashells mostly are.

Anyone got any idea how true this is? I know Llifle can be wrong, so before I repot them all again, I was hoping to hear some other people's thoughts.
I used to fall for the myth that limestone is a natural growth inhibitor. With that said, Calcium needs to be balanced with Magnesium. I get both through the Dyna Gro All Pro 7-7-7 I've been using since 2012, Ca-to-Mg ratio is 4:1 -- pretty much ideal for cacti. IMO O. peruviana should do well with a good Ca-Mg balance, so I wonder if the idea that the species "hates" limestone comes from growers who don't appreciate the importance of Mg in this equation. MikeInOz knows a lot more about it, so hopefully he can give you more properly targeted advice on the matter.
Is it the magnesium or the ion associated with it? If you're using magnesium sulfate to balance, it might be the acidifying property of the sulfate ion doing it.

Either way, I can certainly throw in magnesium sulfate to my fertiliser mix. I make my own from big bags of straight fertiliser. Way cheaper than buying premixed stuff and it lets me mix other fertilisers for my tomatoes and capsicums.
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Steve Johnson
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Re: Oroya peruviana and limestone stopping growth?

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Download wrote: Mon Sep 13, 2021 7:25 amIs it the magnesium or the ion associated with it? If you're using magnesium sulfate to balance, it might be the acidifying property of the sulfate ion doing it.

Either way, I can certainly throw in magnesium sulfate to my fertiliser mix. I make my own from big bags of straight fertiliser. Way cheaper than buying premixed stuff and it lets me mix other fertilisers for my tomatoes and capsicums.
Unfortunately I don't know chemistry, so I can't tell you if the ion association is significant. Here's what I can say...

Toward the end of last summer, I began supplementing my 7-7-7 with Potassium sulfate to correct an imbalance between N and K I wasn't even aware of until Mike educated me on the subject of ferts. Sulfur is another important minor nutrient for cacti -- S deficiencies show up in unnaturally pale-looking cacti, so the Sulfur in Magnesium sulfate should be a nice additional benefit to your plants. Certainly has been for mine as the trace amount of S in my Dyna Gro fert didn't cut it.

By the way, sufficient amounts of Potassium and Calcium share something in common -- they produce stronger spines and strengthen the epidermis of our cacti. As for me, I'll be supplementing the 7-7-7 with a Cal-Mag fert next year. Dig this:

https://www.amazon.com/True-Organic-Pla ... s9dHJ1ZQ==

I dilute 1/2 tsp. of the 7-7-7 per gallon of water. Add 1/4 tsp. of the Cal-Mag, and it effectively doubles the amount of Ca and Mg my cacti are currently getting. Wonderful improvement thanks to the Potassium sulfate supplement this year, and next year should be even better.
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Re: Oroya peruviana and limestone stopping growth?

Post by DaveW »

I remember seeing Graham Charles video on I think it was Matucana where to his surprise he found one grew on a limestone outcrop since evidently limestone is rare in S. American cactus growing areas. Unlike N. America where quite a few cacti grow on it. Which is why the usual recommendation for S. American cacti is a potting soil with a PH slightly on the acid side of neutral. As to whether you need limestone for growth or whether it is a growth inhibitor for cacti that seems to produce conflicting views.

I suppose the real answer is if they get all the nutrients they need and no others are at toxic levels, plus maintain a suitable PH for the substrate they are growing in they will grow. Hence the use of virtually inert mineral potting mixes, or even hydroponics where the nutrient needs are usually supplied by the fertiliser. Steve knows more about nutrients and fertilisers than I do, but if you are growing without any organic content in your mix you need a fertiliser that also provides the trace elements needed. Most these days do, but some for general garden (yard) use depend on the organic content in the soil providing some essential trace elements that are only needed in minute quantities. However these may not be available in a mineral mix in a pot.
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Re: Oroya peruviana and limestone stopping growth?

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DaveW wrote: Mon Sep 13, 2021 12:27 pmAs to whether you need limestone for growth or whether it is a growth inhibitor for cacti that seems to produce conflicting views.
Mike addressed this in a thought-provoking thread he started in July of last year:

http://www.cactiguide.com/forum/viewtop ... 25&t=45060

As long as cacti are getting the right amount of Calcium and Magnesium, IMO the source doesn't really matter. Would the limestone growers know the difference if they were getting their Calcium from somewhere else? My limestone growers (and I have a fair number of them) say no.
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Re: Oroya peruviana and limestone stopping growth?

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It's not the calcium that's the problem, it's the carbonate and the bicarbonate ions which interfere with uptake of many nutrients particularly the metals. Fe is the first deficiency to show up (if all nutrients are present of course AND the pH is too high). Followed by Mn Cu, B, etc.
If you have too much calcium in the form of calcium carbonate in the mix, some plants which ev0lved on acidic soils may not be able to get enough iron. Therefore, you should omit the limestone from such plants (more on that in a minute) and substitute it with another form of calcium. You could use calcium nitrate but that gives too much N for cacti, so you have to use calcium sulphate or gypsum. You can use lime but only if you are bringing peat or other very acidic materials from a very low pH up to about 5.5 to 6. Magnesium sulphate does not alter pH much.
Oroya likes acidic soils. They also seem to grow among grasses so they would not mind an organic content. In fact I would say they would prefer it.

see... https://inaturalist.ca/taxa/441496-Oroy ... wse_photos

Use some peat in the mix for immediate results and check pH as you go. You can also use sulphur but it's easy to over-shoot and does not work that well.

I just noticed you were in Adelaide. With your water I would definitely use peat moss in the mix!
Last edited by MikeInOz on Tue Sep 14, 2021 7:08 am, edited 2 times in total.
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Re: Oroya peruviana and limestone stopping growth?

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For some reason the word e-. vo*l v - ed was removed and replaced with ''disallowed - see forum rules'') ???????
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Re: Oroya peruviana and limestone stopping growth?

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MikeInOz wrote: Tue Sep 14, 2021 6:35 am For some reason the word e-. vo*l v - ed was removed and replaced with ''disallowed - see forum rules'') ???????
I'll PM you about that.
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Download
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Re: Oroya peruviana and limestone stopping growth?

Post by Download »

MikeInOz wrote: Tue Sep 14, 2021 6:31 am It's not the calcium that's the problem, it's the carbonate and the bicarbonate ions which interfere with uptake of many nutrients particularly the metals. Fe is the first deficiency to show up (if all nutrients are present of course AND the pH is too high). Followed by Mn Cu, B, etc.
If you have too much calcium in the form of calcium carbonate in the mix, some plants which ev0lved on acidic soils may not be able to get enough iron. Therefore, you should omit the limestone from such plants (more on that in a minute) and substitute it with another form of calcium. You could use calcium nitrate but that gives too much N for cacti, so you have to use calcium sulphate or gypsum. You can use lime but only if you are bringing peat or other very acidic materials from a very low pH up to about 5.5 to 6. Magnesium sulphate does not alter pH much.
Oroya likes acidic soils. They also seem to grow among grasses so they would not mind an organic content. In fact I would say they would prefer it.

see... https://inaturalist.ca/taxa/441496-Oroy ... wse_photos

Use some peat in the mix for immediate results and check pH as you go. You can also use sulphur but it's easy to over-shoot and does not work that well.

I just noticed you were in Adelaide. With your water I would definitely use peat moss in the mix!
So it is a PH issue and the magnesium sulfate helps bring it down, though not by much.

I use potassium nitrate for K+N, but it's only PH 6.2, so I'm not sure it contributes much here. I might add a little sodium bisulfate instead as I have a bag of it about. Just have to be careful with the dilution.
MikeInOz wrote: Tue Sep 14, 2021 6:35 am For some reason the word e-. vo*l v - ed was removed and replaced with ''disallowed - see forum rules'') ???????
I can not think of any good reasons for that word to be banned.
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Re: Oroya peruviana and limestone stopping growth?

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Download wrote: Wed Sep 15, 2021 2:36 am
MikeInOz wrote: Tue Sep 14, 2021 6:35 amFor some reason the word e-. vo*l v - ed was removed and replaced with ''disallowed - see forum rules'') ???????
I can not think of any good reasons for that word to be banned.
Decision made by the forum's admin when he started CactiGuide. I'll PM you about the reason.
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