Tuff in cactus mixes...?

[nachtkrabb]

Hi folks,
some of you are discussing soilless mixes just like professional chemists. I am impressed but can't really follow as I am not. I grow some cacti soilless, some with soil & pumice, some with soil only, some with soil + pine bark (somehow I would never touch fir bark), & so on. Usually I read up everything I can about a plant before repotting & then mix together what I think might hopefully be the perfect mix.

Today I searched for affordable pumice & stumbled upon this site -- I add the link for other people in Germany. Pumice is sold there eg. in 25l-bags. They also offer tuff in bags, but in small bags of 5l only. They write:

Diese hochwertige Vulkanasche gilt als sehr fruchtbar und stellt die entsprechenden Mineralien der Pflanze sofort zur Verfügung.
Tuff Vulkanasche: Ein Segen für den Garten und Ihre Pflanzen haben dank des Mineralgehalts einen äußerst hohen bodenverbessernden Wert.
Dort wo Tuff eingesetzt wird werden Ihre Pflanzen mit Sicherheit mit schneller Geschwindikeit gedeihen und aufblühen.
Tuff ein sehr wertvoller Dünger und enthält wichtige Nährstoffe wie Phosphor, Calium und Calcium.
Einsatz
Tuff kann unter anderem als Zuschlagsstoff für eine hochwertige Kakteenerde verwendet werden.

This high quality volcanic ash is considered very fertile and immediately provides the appropriate minerals to the plant.
Tuff volcanic ash: a blessing for the garden and your plants have an extremely high soil improving value thanks to the mineral content.
Where tuff is used, your plants will certainly flourish and blossom with rapidity.
Tuff is a very valuable fertilizer and contains important nutrients such as phosphorus, calium and calcium.
Use
Tuff can be used, among other things, as an additive for a high quality cactus soil.
Translated today with www.DeepL.com/Translator -- lazy me...

Do you use tuff in your mixes? If so:
* For which plants?
* In which quantities? Like: 1spoonful per 2l-pot, or 20% of the mixture, or...?

Thank you.
Nachtkrabb

To me this question is a bit crazy as I know tuff in the form of building blocks. The romans loved it, transported it from Germany to Italy for quality reasons, & their buildings partly still stand after 2T years. The Suebians in the South-West of Germany have always used it as a local, very reliable and durable building material. And now putting THAT into my cacti pots..?! Crazy.

[jerrytheplater]

No, I don't use Tuff. Why? Never thought of it. Would I try it? Yes. If I could get it easily. Never looked yet.

[nachtkrabb]

No, I don't use Tuff. Why? Never thought of it. Would I try it? Yes. If I could get it easily. Never looked yet.

Hi Jerry,
thanks for considering. How would you use it? Just small quantities, or really in good dollops?
N.

[jerrytheplater]

I'd be guessing at the keyboard to give a specific answer. More research is needed.

[MrXeric]

Seems like tuff or volcanic ash is used as a silicon fertilizer (a plant micronutrient). The advantage of using tuff is that the silica (silicon dioxide) is amorphous, a form that apparently is easier for plants to take up compared to crystalline silica (quartz).

I found an American company that sells the stuff: https://montanagrow.com/. They give a chemical analysis of their product (72-76% silica with other trace minerals), but that really depends on the source of the ash. You can probably ask your German company for the analysis of their product.

They provide a list of benefits for using amorphous silica for plants (I assume all plants?), but you can find that with more detail elsewhere online. https://montanagrow.com/uses If you scroll down they provide guidelines for use, though it's not clear whether those guidelines are meant for their powdered or granular product. As a rough conversion, seems they recommend to use 1 to 3 spoonfuls of tuff per 2L of substrate (assuming a 15mL spoon).

[jerrytheplater]

So it sounds like it is being used as a soil amendment, not as the soil itself.

[anttisepp]

I do myself soil mixture which contains modest part commercial soil where usual component is turf (we have great amounts of turf in our country). I never noticed nothing harmful and my plants feel nice.

[nachtkrabb]

I do myself soil mixture which contains modest part commercial soil where usual component is turf (we have great amounts of turf in our country). I never noticed nothing harmful and my plants feel nice.

Dear Anttisepp, "turf" will be the soil that grass grows upon...? -- "Tuff" on contrary is volcanic ashes.
I know the vikings built houses out of turf, archaeologists found them in Greenland & in North America. In my country, we sometimes still use tuff stones.
This is why I am asking... It wasn't & isn't that obvious to me...
N.

[anttisepp]

OK, not only fool but blind also

[nachtkrabb]

OK, not only fool but blind also

When writing at such an unearthly hour as 7am ...? Well...
N.

[Steve Johnson]

Okay, I did some research indicating that silicon (Si) may be more important to the healthy growth of our cacti and succulents than we may realize. Check out this article:

https://hydrobuilder.com/learn/silica-for-plants/

IMO potassium silicate (AKA tuff) cannot be recommended in cactus mixes for the reasons described in the article. If you read it through, you'll find that mono silicic (AKA orthosilicic) acid is a much better supplement we can add to our watering solutions diluted with fertilizer, and once again you'll see why it is. Although a number of online sources state that Si is considered to be a nonessential nutrient, I see a good argument in favor adding a silica source that's readily available to your plants. I can't make any specific recommendations just yet, but after I dig into this deeper, I may be able to.

[Steve Johnson]

And now I have some recommendations. First, you'll want to buy mono silicic acid (MSA) in liquid form. The product(s) you find will depend on where you live. Once you select your product of choice, do the following:

• Write down the percentage on the label. % x 0.292 gives you the percentage of silicon (Si).

• Calculate the dilution (dosage) of the product going into your watering solution. Aim for 50 parts-per-million Si.

The product I selected is Alchemist Stout MSA available on Amazon here:

https://www.amazon.com/Alchemist-Stout- ... 466&sr=8-4

The Alchemist Stout contains 1.25% MSA. 1.25% x 0.292 = 0.365% (3650 ppm) Si. 1/4 cup diluted in a gallon of water gives us 57 ppm Si -- close enough. (If you'd like the calculation there, it's 3650 x 0.015625 = 57 ppm.)

Going through a few hydroponics websites, the general recommendation is for 100-150 ppm Si. However, that applies to agricultural crops, not cacti, so I believe a more conservative approach in terms of dosage will be better for cacti over the long haul. Do all cactus species use Si? From what I could find in the scientific literature online (and there isn't much), some do, some don't. However, nothing definitive, so you won't know which is which regarding what you have in your collection. With the conservative number (50-60 ppm) my thinking is that if it doesn't help, at least it can't hurt cacti which don't use Si.

Where in the world are you? The answer has to do with my last set of recommendations:

• Growers living in the northern hemisphere. It's too late in the growing season to find out if supplementing your fertilizer with MSA would lead to any improvements, so you can put this on your "to-do" list next spring.

• Growers living in the tropics. Your growing season is year-round, so you can starting doing it right away if you're so inclined.

• Growers living in the southern hemisphere. Our fall is your spring for cactus growing season, so you can start supplementing your fert with MSA then.

If we do see growing improvements using MSA, what should we look for? That I can't answer yet, so maybe we have a few members who can tell us what they are. If not, I'll find out for myself next year.

[Tom in Tucson]

This post might be a little OT, so please forgive me. For years (since when I started college), I've always been "on the lookout" for soil appropriate for growing cactus. Long ago while looking for cacti near Mono Lake CA, I found what I thought were huge deposits of pumice. I tried growing "difficult" cacti in this medium, and to my delight, I found that it worked like a "charm". I eventually used up all of what I collected (very long ago), but I was determined to get more. some day. This medium looked like Styrofoam pellets when it disintegrates, (but not as light weight). 17 years ago I finally went a little out of way (when returning from a trip to Oregon, then through Nevada, and towards the Owens Valley) and successfully retraced my route to the the approximate location. I gathered as much as my car shocks could handle!

I've since learned that it's not actually pumice, but is more likely to be a form of tuff.

Does anyone know what to call my discovery based on my description?

[Steve Johnson]

For years (since when I started college), I've always been "on the lookout" for soil appropriate for growing cactus. Long ago while looking for cacti near Mono Lake CA, I found what I thought were huge deposits of pumice. I tried growing "difficult" cacti in this medium, and to my delight, I found that it worked like a "charm". I eventually used up all of what I collected (very long ago), but I was determined to get more. some day. This medium looked like Styrofoam pellets when it disintegrates, (but not as light weight). 17 years ago I finally went a little out of way (when returning from a trip to Oregon, then through Nevada, and towards the Owens Valley) and successfully retraced my route to the the approximate location. I gathered as much as my car shocks could handle!

I've since learned that it's not actually pumice, but is more likely to be a form of tuff.

Does anyone know what to call my discovery based on my description?

What you have is actually tufa -- sounds similar, but it's not the same as tuff:

https://en.wikipedia.org/wiki/Tufa

Here's some additional info:

https://www.mindat.org/min-50847.html

Great for limestone-growing species, not so great for species that aren't ev0lutionarily adapted to native desert soils containing limestone.

[Tom in Tucson]

Thanks for the quick reply. I checked both of the links, but that is not the appropriate description for the composition (limestone or sedimentary origin) of what I found. Let me explain further:

Mono Lake does have tufa towers, but there are also other types of rock present, because of the Mono-Inyo Craters chain. I saw a cinder cone adjacent to where these small, unusual rocks were found, and I assumed that this "pumice" was from a volcanic explosion. I wish I had an image to include.

Like I said before, it's like styrofoam pellets when they disintegrate, (but not as light weight) I will do more research on what to call this stuff. Whatever it's called, it's one of the best additives I've ever used on all types of cactus including, (but not limited to) those that usually prefer limestone.

Here is an image I just found of the gravel in question: https://www.flickr.com/photos/pawoodhea ... otostream/