Fertilizers explained (2-part presentation) -- with 6/2023 update

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
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Steve Johnson
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Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

Took a few tries before I figured out how I should be approaching this...

I wanted to design my spreadsheets so that they would be simple without being simplistic. However, as a firm believer in the maxims "trust, but verify" and "show your math!", I also wanted to have the percentage and ppm calculation procedures on the spreadsheets in case growers want to see how I arrived at the numbers. This should also come in handy for growers who'd like to know how they can do their own calculations with ferts that are different from the ferts in my spreadsheets.
jerrytheplater wrote: Tue Mar 14, 2023 3:57 amAnd yes, it is very important to say how strong/how concentrated your fertilizer solution is in terms of Nitrogen. (I've been calculating that for years really. Ever since I started wondering when given instructions to use Tomato fertilizer at 1/2 strength or 1/4 strength. Never liked that.)
I never did either, and iann certainly didn't when he tried to point out the importance of knowing the ppm dosages going into our cacti. Wish he had emphasized that when he was active on the forum, but we can make up for it here -- with spreadsheets. Don't know if I'll have the time for it this week, so I'll be happy to email you with my Excel file over the weekend if not before then.
jerrytheplater wrote: Tue Mar 14, 2023 3:57 amBy the way, I saw my friend has some Plant Products No Stretch fertilizer: 15-0-20. https://www.plantproducts.com/ca/viewpr ... p?pid=1303
Interesting. Unfortunately not something I would recommend for cacti, although it's nice to see that the fert actually has a decent amount of Mo.
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Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

I was looking at what the spec sheet said, "No-Stretch works to harden plant structure and prevents leggy growth. Use towards the end of the crop cycle for compact sturdy growth and to keep internodes short." Goes along with what he said about too much P, that it can cause too much growth, increasing internode distance.

I'm still thinking about an African Violet fertilizer with lower P. I noticed that that Ferty 2 15-5-25 mentioned its use on African Violets. I could use No Stretch and supplement with Potassium Mono Phosphate to add in P. My gears are turning.
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.
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Steve Johnson
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Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

jerrytheplater wrote: Tue Mar 14, 2023 12:57 pmI'm still thinking about an African Violet fertilizer with lower P. I noticed that that Ferty 2 15-5-25 mentioned its use on African Violets. I could use No Stretch and supplement with Potassium Mono Phosphate to add in P. My gears are turning.
Oh, great -- now my wheels are turning! :lol: I'll admit that I'm "hard-wired" to using liquid ferts which suit me because I have such a small collection, and it uses only 3 or 4 gallons of water per month in the growing season. However, I do realize that some (maybe most?) of our members are growing hundreds or thousands of plants, so I can see why dry fertilizers are more economically feasible for them. Such being the case, your idea expands the number of choices we have available based on the size of one's collection. I'll take a stab at this and see if I'm able to come up with a good spreadsheet for the No Stretch plus a Potassium Mono Phosphate supplement that'll fly for the members who could use it.

I haven't started the fert recipe "library" sticky yet, but I hope to get it going soon. When I do, I'll include the various ferts' countries of origin and availability so members will know about what they can get according to where they live.

Update: Spoke too soon -- see my next post.
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Steve Johnson
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Re: Fertilizers explained (2-part presentation)

Post by Steve Johnson »

Just so that everyone can see this, here is the analysis for Plant-Prod Solutions 15-0-20 No Stretch:

Total N = 15% (Nitrate N = 12.2%, Ammonium N = 2.8%)
K2O = 20% (K = 16.6%)
Ca = 3%
Mg = 1.5%
S = 0%
That's a red flag. Sulfur is an important minor nutrient, and I would be leery of any fertilizer which doesn't include it. The only workaround I can think of would be supplementing the No Stretch with good old Epsom salt (AKA magnesium sulfate), but that'll mean higher Mg in relation to Ca, and the Ca-Mg ratio in the No Stretch is already poor. Since Ca will need to be at least 3 times higher than Mg, we'll need another calcium source, and believe it or not, we can make our own water-soluble calcium. Here's how to do it:

https://www.microfarmguide.com/water-soluble-calcium/

If you go through the instructions, you'll see that it's a labor-intensive process. How many of us would be willing to go that far? IMO this is a rhetorical question because there's another red flag:
  • "No-Stretch works to harden plant structure and prevents leggy growth. Use towards the end of the crop cycle for compact sturdy growth and to keep internodes short."
No Stretch has an application very specific to crops, and using it for cacti is like trying to fit a square peg in a round hole. Jerry, I don't want you to go away empty-handed, so check this out:

https://www.plantproducts.com/ca/viewpr ... p?pid=1268

Only thing missing is Ca, but we can supplement it with -- Nitrogen-free TPS CalMag, one of the tools I already have in my fert supplement toolkit. I think this fert holds a lot of promise, and it rates further investigation.
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Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Plant Products fertilizers are sold to commercial growers. It might be difficult to get on your own.

Don't spend your time making a spreadsheet for me. If I do use this, I'll be using a spreadsheet to craft the fertilizer.

It is meant to be added to water for use. Don't boil the water after mixing as you'll boil the Boron away. I plan to boil my rainwater mixture to sterilize it before using it. I am thinking of making a close to saturated solution of it, if I do use it. They list the solubility at 15C as 400 grams per liter. At 25C it is 510 grams per liter. The Ca and Mg are there as Nitrates. More Ca(NO3)2 could be added. It is a neutral fertilizer regarding pH.

Adding sulfur might be a bit difficult as it might precipitate with the Ca and Mg. But this is the same situation with the Flora products. CaSO4 has a solubility of 2.6 grams per liter. We are nowhere near that level, so it may work.
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.
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Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

The eggshell process is making Calcium Acetate. I'd use dolomitic limestone to get Mg too. Or pure limestone for just Ca.
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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Re: Fertilizers explained (2-part presentation)

Post by 7george »

jerrytheplater wrote: Wed Mar 15, 2023 2:05 am I'd use dolomitic limestone to get Mg too. Or pure limestone for just Ca.
Tap water usually contains enough carbonates of these elements, spring water too. Just acidifying that water would help to get them in soluble form. Or to extract them from rocks and sand in the soil mix.
If your cacti mess in your job just forget about the job.
°C = (°F - 32)/1.8
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Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

They are soluble in your tap water, unless you see particles coming out of your tap!
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.
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Re: Fertilizers explained (2-part presentation)

Post by quod »

Hi guys,
As a novice to cacti and succulents, Thankyou so much for this discussion! Its very informative and so easy to understand once the Pdf pictures were made and posted. I was happy to learn that the General Hydroponics solutions were used for the fertilizer since I already have them for my semi-hydro tropical plants. I do have one question if anyone can help answer.

I'm currently getting ready to sow some seeds and I was wondering if I choose to germinate the seeds in a completely non organic medium, should I use a diluted amount of the non-organic fertilizer solution posted here, or should I wait and go with regular tap water until the seedlings are a little more established.

Thank you again for this discussion, it really answers alot of questions I had about fertilizers and gives many resources for further reading.


ps: I noticed alot of papers posted are paywalled and are unable to be read. My partner works in a lab and constantly deals with these problems, so she uses a website called Sci-Hub https://sci-hub.se/ to access paywalled articles and papers. It won't work for every paper but is a nice resource to check if you can't get a hold of the author to provide you a copy
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Re: Fertilizers explained (2-part presentation)

Post by jerrytheplater »

Hi quod.

Thanks for that link. I'll try it.

Re fertilizers: Don't fertilize your seeds until you get germination, and then very dilute. I fertilize at 50 ppm N, so that is what my plants get. Others go higher on the N. Still others mix in fertilizer to the potting mix-but they use a more organic containing mix.

So, you say you are thinking of a non-organic medium ( I suppose you also mean 100% mineral). If that is true, then no ferts till you see seedlings. It will just pass out the drainage holes doing nothing.
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.
quod
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Re: Fertilizers explained (2-part presentation)

Post by quod »

Thanks for the quick response!
I will go ahead and hold off on the fertilization until germination. And yes I do mean a 100% mineral medium consisting of pumice, black lava rock, chicken grit(granite), perlite, sand, and zeolite. I will probably do a side by side experiment of all non-organic medium vs partially organic medium to see what works better in the long run but my guess is that the results will vary based on the different genera grown.

Thanks again for the help and advice, I really appreciate it.
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Re: Fertilizers explained (2-part presentation)

Post by zpeckler »

Thanks for the update on your fertilizer regimen, Steve. Last year I used the All Pro regimen and I got some of the best growth my cacti had in years! I'm doing this updated regimen this year.

Here's a question I've been mulling over for a bit... Using your fertilizer regimen and a mineral mix ((or in my case, a *mostly* mineral mix--100+ degree heat during summer means I need about 25% organic otherwise things dry out too quickly)) do you have an opinion on amending the growing medium with some pelletized dolomitic limestone and gypsum for those species that grow on limestone in habitat?
--------------------
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Re: Fertilizers explained (2-part presentation)

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zpeckler wrote: Fri May 05, 2023 5:11 pmdo you have an opinion on amending the growing medium with some pelletized dolomitic limestone and gypsum for those species that grow on limestone in habitat?
I'm not Steve, but I do have a comment on Pelletized Limestone. Those pellets are comprised of very finely ground limestone held together loosely by a water activated binder. Once it gets wet it falls apart. Then the particles are very easily dissolved compared to granules of gypsum. The gypsum granules will dissolve much more slowly and release the calcium slowly. Better choice than the pelletized limestone.
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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Re: Fertilizers explained (2-part presentation)

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zpeckler wrote: Fri May 05, 2023 5:11 pm Thanks for the update on your fertilizer regimen, Steve. Last year I used the All Pro regimen and I got some of the best growth my cacti had in years! I'm doing this updated regimen this year.

Here's a question I've been mulling over for a bit... Using your fertilizer regimen and a mineral mix ((or in my case, a *mostly* mineral mix--100+ degree heat during summer means I need about 25% organic otherwise things dry out too quickly)) do you have an opinion on amending the growing medium with some pelletized dolomitic limestone and gypsum for those species that grow on limestone in habitat?
Before I get to your answer, I just wanted to mention that I gave all of my cacti their first deep watering of the growing season a couple of weeks ago -- pure rainwater and nothing more. Unfortunately things here in SoCal are cooler than I'd like, so I'm not sure if watering this weekend would be a good idea. Next weekend? Definitely yes, and the collection will be getting its first feeding under my new fert regimen. Although I did well with the Dyna Gro All-Pro over the years, I'm looking forward to even better results with the General Hydroponics ferts and supplements.

Adding a small amount of limestone and/or gypsum to your mix is a good idea depending on the species you're growing. I don't only because A. I don't have enough confidence to know that I'm adding the right amount, and B. I found that adding a small amount of CalMag supplement to the watering solution is easier. 1/4 tsp. of TPS CalMag per gallon did wonders last year, so I'll include it when the cacti get their regular feeding this year. If you'd like to go the limestone/gypsum route, MikeInOz is an expert, so this may be helpful -- from "The Cal-Mag of my dreams?" thread:
MikeInOz wrote: Thu Dec 29, 2022 6:19 amA lot of the Texas and Northern Mexico plants grow in soils with both limestone and gypsum so I give them both. Things like arios, epithelanthas, many thelos, all astros, all coryphanthas and escobarias many mamms ( you have to check) pelecyphora, etc. No need to add limestone more than once. Gypsum is much more soluble so I add a bit at the start of each growing season. If you can use particles of gypsum which are say 2 - 3 mm in size they will probably last 2 years or more. Limestone will basically last forever.
All the other things like notos, rebutias, lobivia etc get a little gypsum but no limestone as they like more acid conditions. If you regularly add trace elements (especially if they are chelated ) there is not so much need to worry about the pH. (but I still try to keep it around 5.5 - 6). I have only seen severe chlorosis in 2 cacti. An echinopsis and a Neobuxbaumia. If it gets too bad there is no saving the plant. So most things seem to tolerate a fairly wide range.
With that said, cacti can get calcium from various sources, so IMO the source doesn't matter as long as it's in a form available to the plants. Speaking of...

My ability to store rainwater is limited to 4 1-gallon jugs, and 3 got used up already, so I'll have acidify my tap water during the rest of the growing season. Calcium bicarbonate = temporary hardness in the tap water which can be neutralized by acidification with:
  • 5% white vinegar. The byproduct of acidification is calcium acetate in the watering solution.
  • While vinegar is fine for small collections, growers with big collections need something more concentrated. If that's the case, I recommend citric acid because it's a lot safer than phosphoric and sulfuric acids for home use. The byproduct of acidification with citric acid is calcium citrate in the watering solution.
Unlike the insoluble calcium carbonate left behind when tap water evaporates, calcium acetate and calcium citrate are highly soluble -- and a good source of calcium available to our plants. Obviously not the main source, but it's a nice little bonus.

P.S. I just saw Jerry's response, and I agree -- stay away from the pelletized limestone.
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Re: Fertilizers explained (2-part presentation)

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jerrytheplater wrote: Fri May 05, 2023 10:38 pm
zpeckler wrote: Fri May 05, 2023 5:11 pmdo you have an opinion on amending the growing medium with some pelletized dolomitic limestone and gypsum for those species that grow on limestone in habitat?
I'm not Steve, but I do have a comment on Pelletized Limestone. Those pellets are comprised of very finely ground limestone held together loosely by a water activated binder. Once it gets wet it falls apart. Then the particles are very easily dissolved compared to granules of gypsum. The gypsum granules will dissolve much more slowly and release the calcium slowly. Better choice than the pelletized limestone.
Thanks a bunch for the advice, Jerry. I've got a bunch of the limestone and gypsum on hand because every freaking year my hot peppers get blossom end rot, so I gotta amend the soil like crazy. The fertilizer regimen described in this thread is working really well for my cacti, and I'm reluctant to try and fix something that ain't broke, but I would like to try and mimic habitat as much as I can. Maybe I'll try and find some limestone gravel, if that's a thing.
--------------------
Zac

Butte County, CA, USA
USDA Zone 9b
Mediterranean climate; hot, dry, sunny summers with rainy, moist, mild winters.
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