Seeking knowledge regarding feeding of Astrophytum, Lophophora, Ariocarpus, Copiapoa and Trichocereus.

[HudsonLH]

Do you have other evidence backing your claim? It will be an interesting read.

From my Member Blogs thread, start here and you'll have a lot (and I mean a lot) to go through:

http://www.cactiguide.com/forum/viewtop ... 10#p365647

The starting point I'm giving you here begins my 2019 end-of-summer review. The only evidence I have comes from my own experience, so you can decide for yourself whether or not I'm able to back the claim.

By the way, commercial nurseries are interesting in growing salable plants. Their growing practices may be (and probably are) different from the practices being followed by collectors who are interested in the long-term health of their plants.

Steve,

Thank you for the link.

I am not aware of any literature suggesting that higher P lower N will lead to long-term negative health outcomes in cactaceae. If we are using cultivation experience as a benchmark, the nurseries I reference have astrophytums in their personal collections that have been passed on through generations. However, I am open to having my mind changed, and will be reading through your experiences tonight.

H

[DaveW]

"Dave: If I could jump in here for Steve. I just Googled your Tomorite so I could read the label myself. It is labeled in two ways. The elemental way is 4% N-1.3% P-6.6% K, which is the way the ratio Steve got from Mike is stated. Reduce that so N is 1 and you get 1-0.32-1.65 which is also excellent-you can use it as is."

Thanks Jerry I wondered if I just had to divide it by 4 to get a comparable ratio. Yes British gallons are larger than American ones and British ton's are heavier too. You Yanks don't have everything bigger! LOL

[jerrytheplater]

To get to a more reasonable 50 ppm N, you should dissolve 0.3 grams fertilizer in a liter to fertilize your cacti by watering your pots. I do let my fertilizer water wash over my cacti, but I don't grow any with a bloom on the surface that might be damaged and I am only using 25 ppm N. I also water in between fertilizing with plain water which rinses off the plants.

Narubest: I was thinking today while at work about you using 0.3 gm/liter of your dry fertilizer.

That 0.3 gm will only be a few granules, or maybe one, depending on the size of your product. The potential problem here is that your fertilizer is a mixture of different compounds. Each granule may be made up of an ingredient, and not a well mixed combination of all the ingredients. Does that make sense? An ideal fertilizer would be composed of a well mixed composition where each particle of each ingredient is the same size. Then that fertilizer could be granulated and each granule would match the composition stated on the label. But, I doubt that is the case.

The attached pictures are of a trace mineral product called Nutritrace CSM. It is composed of several chelated metals. Commercial greenhouses potentially could use the entire 25 lb bag when applying it. They will get exactly what the label says since they are dissolving the entire bag. The problem comes when you only want to measure out a pound in order to sell it. The product will segregate into its components to some degree since they are not all the same size, and density. I mix the container as best as I can and let the dust settle before opening the container. You will see one photo looks mostly well mixed, while the other is not. Same product.

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So, I would suggest grinding your fertilizer in a blender to get a fine powder. You will need to do it in batches, but you only have 500 grams, not 25 * 454 grams. Beware of breathing the dust, I have developed a contact dermatitis allergy to the CSM, especially the copper. I break out into an itchy blistered area if in contact on sweaty skin. I did grind my CSM, but no more. It is too dangerous for me.

[Steve Johnson]

Steve,

Thank you for the link.

I am not aware of any literature suggesting that higher P lower N will lead to long-term negative health outcomes in cactaceae. If we are using cultivation experience as a benchmark, the nurseries I reference have astrophytums in their personal collections that have been passed on through generations. However, I am open to having my mind changed, and will be reading through your experiences tonight.

H

From August 2020, this is when Mike corrected me on what I thought I knew about the right type of fertilizer for cacti:

http://www.cactiguide.com/forum/viewtop ... er#p377330

I may have some additional info for you, but I'll need to dig through my email this weekend. The correspondence I'll be look for comes from two sources. One is John Trager, curator of the Huntington Botanical Garden's desert collection. A wizard of a grower, and he's been active there for at least 20 years. Same goes for my other source, Miles Anderson of Miles' To Go in Cortaro Arizona. I emailed both of them asking about the ferts they use. If I still have the email, I'll get back to you with some numbers.

[Steve Johnson]

Well, nerts -- I can't find the email from Miles, but I did find the one from John at the Huntington -- and this kinda surprised me...

His fertilizers are Peter's 13-2-2 and Liquinox 12-5-5. He said that he uses them at "1/3 strength", although it doesn't mean much without knowing what's indicated on the product labels. Neither here nor there, but please note the substantially lower P in relation to N. If you go to the Huntington's desert greenhouse, you'll see plenty of cacti in flower.

John brought up a couple of key points in his email (from August of last year, by the way):

"My opinion, like most, is based merely on my individual experience which I consider as anecdotal as any rather than research based. Even then, the research results are only as good as the experimental design and are dependent on factors considered and those that might not have been...it sounds like your Australian correspondent has a more data based approach to fertilizer selection. However, the proof is in the potting. If your plants are performing satisfactorily, keep doing what you are doing. On the other hand, one can tinker endlessly with one’s horticultural techniques. That is part of the fun for many."

I realize it's a matter of personal preference, but my preference is for Mike's data-based approach. I give him endless amounts of credit for recommending Potassium sulfate as a supplement to the Dyna Gro 7-7-7 I've been using since 2012, although doing it toward the end of last summer wasn't enough time to see any noticeable results yet. 4 months into this year's growing season, I sure see them now -- P lower than N, K higher than both, and the results are pretty amazing. I usually put annual end-of-summer reviews up on my Member Blogs thread, but I didn't have enough time for a 2020 review. With another summer ending in a couple of months, I'll compare the difference between what the cacti looked like before Potassium sulfate came into the picture and what they look like at the end of a full growing season with it. Should make for a nice 2021 review.

There may be a good argument in favor of higher-P fertilizers for growing cacti in a tropical climate, but I'll leave that up to the experienced growers who actually live in the tropics. For the rest of us, IMHO Mike has it right.

[DaveW]

Garden Centres in the UK usually sell what we call potting grit, which is actually small gravel. Maybe your garden centres do too? However things are usually cheaper from builders merchants if they stock the equivalent. We also use this grit for top dressing the pots to save the soil in the pot splashing over the plant when watering.

https://www.bing.com/images/search?view ... ajaxserp=0

[HudsonLH]

Well, nerts -- I can't find the email from Miles, but I did find the one from John at the Huntington -- and this kinda surprised me...

His fertilizers are Peter's 13-2-2 and Liquinox 12-5-5. He said that he uses them at "1/3 strength", although it doesn't mean much without knowing what's indicated on the product labels. Neither here nor there, but please note the substantially lower P in relation to N. If you go to the Huntington's desert greenhouse, you'll see plenty of cacti in flower.

John brought up a couple of key points in his email (from August of last year, by the way):

"My opinion, like most, is based merely on my individual experience which I consider as anecdotal as any rather than research based. Even then, the research results are only as good as the experimental design and are dependent on factors considered and those that might not have been...it sounds like your Australian correspondent has a more data based approach to fertilizer selection. However, the proof is in the potting. If your plants are performing satisfactorily, keep doing what you are doing. On the other hand, one can tinker endlessly with one’s horticultural techniques. That is part of the fun for many."

I realize it's a matter of personal preference, but my preference is for Mike's data-based approach. I give him endless amounts of credit for recommending Potassium sulfate as a supplement to the Dyna Gro 7-7-7 I've been using since 2012, although doing it toward the end of last summer wasn't enough time to see any noticeable results yet. 4 months into this year's growing season, I sure see them now -- P lower than N, K higher than both, and the results are pretty amazing. I usually put annual end-of-summer reviews up on my Member Blogs thread, but I didn't have enough time for a 2020 review. With another summer ending in a couple of months, I'll compare the difference between what the cacti looked like before Potassium sulfate came into the picture and what they look like at the end of a full growing season with it. Should make for a nice 2021 review.

There may be a good argument in favor of higher-P fertilizers for growing cacti in a tropical climate, but I'll leave that up to the experienced growers who actually live in the tropics. For the rest of us, IMHO Mike has it right.

Steve,

Thanks for the write-up. I apologise for my late response - research funding has been reduced this year due to COVID-19 and grant season has become even more bloodthirsty than usual.

I do not mean to be unnecessarily contrary, but I have some concerns:

1) Mike provided very little evidence to support his claims that high P/low N would lead to negative outcomes in cacti. This is something that is also noted in the linked thread (http://www.cactiguide.com/forum/viewtop ... er#p377330).

His first study described Mexican soil characteristics while the other examined foliar stiochiometry of plants in the Sonoran desert. These reported the conditions that cacti would grow naturally in, but did not provide any support that high levels of P would lead to deficiencies. I also see little value in applying a general NPK utilization chart to cactaceae given that their optimal nutritional needs are very different from other plant families. It does not matter that cacti grow together with other plants in habitat.

I think claims that go against conventional literature should be substantiated by some sort of experimental evidence. This can be in the form of peer-review literature or non peer-reviewed home experiments. At this stage, the claim (high P/low K = bad) is purely anecdotal and quite unconvincing.

For now I'll look forward to your 2021 review. Please keep me posted.

H

[Steve Johnson]

I think claims that go against conventional literature should be substantiated by some sort of experimental evidence. This can be in the form of peer-review literature or non peer-reviewed home experiments. At this stage, the claim (high P/low K = bad) is purely anecdotal and quite unconvincing.

As John Trager said, the proof is in the potting -- the only experimental evidence that counts will be the results you get from experimenting on your own cacti. Unless you start losing plants before then, you'll know in about 20 years if "conventional wisdom" in the literature is right or wrong.

Since you're new to the hobby, I'll give you the benefit of two things I learned when I joined the forum about 10 years ago. First, local conditions rule -- growing practices in one person's climate may not apply to growers living in a substantially different climate. Not sure if this is germane to the discussion, but worth mentioning anyway. Second, cultivation is the art of observation. It takes practiced experience to know what looks normal and what doesn't, so if your powers of observation are keen, you'll notice how even the smallest changes can be significant. There's no substitute for gaining your own experience over time, and the last thing I'll say is -- be patient. Impatient growers don't last long in the hobby.

[abhikjha]

My limited view and understanding is for a pure mineral mix, recommended fertilization regime is to follow what you would do in a hydroponics farming.

Even if a bit of soil is added, cactus growers all over the world advocate that majority of the mix should be mineral for free drainage. So in essense it's a hydroponics farming to a very large extent.

If we all agree on that, then below link could be useful. General Hydroponics is a big, established and credible name in hydroponics farming since 1970s. They recommend (7 6 11) if you add Gro, Micro and Bloom NPK constituents. If you work out the real constituents of this NPK (after adjusting P and K, multiplying P by 0.436 and K by 0.83), it will come out to be 1:0.37:1.30. This is very close to what Mike has been suggesting.

https://generalhydroponics.com/products/flora-series/

[HudsonLH]

I think claims that go against conventional literature should be substantiated by some sort of experimental evidence. This can be in the form of peer-review literature or non peer-reviewed home experiments. At this stage, the claim (high P/low K = bad) is purely anecdotal and quite unconvincing.

As John Trager said, the proof is in the potting -- the only experimental evidence that counts will be the results you get from experimenting on your own cacti. Unless you start losing plants before then, you'll know in about 20 years if "conventional wisdom" in the literature is right or wrong.

Since you're new to the hobby, I'll give you the benefit of two things I learned when I joined the forum about 10 years ago. First, local conditions rule -- growing practices in one person's climate may not apply to growers living in a substantially different climate. Not sure if this is germane to the discussion, but worth mentioning anyway. Second, cultivation is the art of observation. It takes practiced experience to know what looks normal and what doesn't, so if your powers of observation are keen, you'll notice how even the smallest changes can be significant. There's no substitute for gaining your own experience over time, and the last thing I'll say is -- be patient. Impatient growers don't last long in the hobby.

Steve,

While I am new to the forum, I do not consider myself new to this hobby - it has been close to 7 years and I now have a decently lucrative side business growing and selling rare gymno and astro cultivars. Admittedly my interests are focused on very specific genera but I do keep other cacti.

I do not believe that horticulture is an art - it is a science. Observations without appropriate controls will not be very useful. As of right now I don't think there is even enough information for preliminary hypotheses. Everything I have read so far has been conjecture. This might change with your 2021 review which I look forward to. I do appreciate you searching through your old emails.

H

[Steve Johnson]

While I am new to the forum, I do not consider myself new to this hobby - it has been close to 7 years and I now have a decently lucrative side business growing and selling rare gymno and astro cultivars.

Bad assumption on my part -- sorry about that.

If I had the time and growing space for it, I would've tested my cacti with different fertilizers to see which fert works best in terms of overall health and growth. I'm sure we'd be looking at 5-10 years (maybe longer) to wait for valid results -- unfortunately a moot point since I don't have either. However, I know what struggling cacti look like, and if any of mine failed to thrive within the first 5 years, I would've been trying to discover problems and how to correct them. As far as I'm concerned, I got lucky, so my growing practices seem to be holding up. You may be in a better position to test your cacti with high-P and low-P fertilizers. If you've already done that, let me know about your findings. If you haven't, but you can point me toward peer-reviewed studies comparing high-P and low-P ferts on an "apples-to-apples" basis, I'm all ears. Cacti and succulents are ev0lutionarily adapted to nutrient-poor native soils, so comparison studies dealing specifically with those types of plants under cultivation would be interesting.