Steve Johnson wrote: ↑Thu Feb 16, 2023 4:07 am
MikeInOz wrote: ↑Thu Feb 16, 2023 1:51 amI only skimmed the article Steve because I have to surrender the computer, but I have found a couple of speculative nonsense statements. For example, the Astro with lots of flower buds. It obviously has not been ''over fertilized'' looking at the plant itself, which appears normal in every way
- not bloated - not stretched - a good even covering of scales and areoles. So clearly there is another reason for all the flower buds. Another statement where ''this is the way Mammillaria schumanii is supposed to look.'' Says who? I certainly would not want mine to look like it's close to death. But maybe that's just me.....
Hi Mike,
Certainly not a high priority, but when you can go through those articles at your leisure, I think you'll concur with a couple of things I noticed:
- A dismissive attitude on the part of Dag Panco toward cacti that are properly fed by growers who know what they're doing. I wouldn't want my cacti looking like they're on death's door either.
- Neither author seems to know much (if anything) about the role of nutrients available to cacti under cultivation when growers use ferts that are well-balanced and include a full spectrum of all nutrients.
With respect to Mr. Panco, I do see examples of what seem to be abnormal growth in his article. What I don't see are precise descriptions of what caused the abnormalities -- "a plant influenced by an excess of fertilizers" tells us nothing. What I also don't see -- examples of cacti being grown with excessive P in the fert. Since your eyes are much better-trained than mine, maybe you do. If so, point me to the pages where you see them, and I can pull the photos out from the PDF for reference.
Why am I making such a big deal out of all this? Here's why -- from Part 1 of my Fertilizers Explained presentation:
Steve Johnson wrote: ↑Sun Jan 22, 2023 6:53 am
NPK ratio
This ratio determines whether you have well-balanced or unbalanced proportions of N, P, and K in your fert. The ideal NPK ratio for cacti and succulents is 1:0.4:1.1-1.7. Contrary to what you may have heard or read elsewhere, high-Phosphorus ferts should be avoided --
when P is higher than N, poor root growth and abnormal stem growth will be the eventual consequence of the plant's longterm exposure to a high-P fert.
I'm not satisfied with that because I don't think it's specific enough. Besides, "show and tell" would be better than making do with simply "tell" -- if I can include photographic examples of what cacti exhibiting the signs of excessive P look like, growers will know what to look
for in case their cacti have those problems. And if they do, they can look for a lower-P fert to correct the situation before the problems become even more of a problem over time.
Just a few thoughts on the articles.
The over production of flowers (pages 83 and 88) attributed to ''over fertilization'' ( whatever that is) does not seem plausible.
To me, it looks more like some kind of hormone issue which is causing that freak flower production from new and old areoles. Whether the plants have been given some unknown substance, or whether it was in the water or substrate I don't know. But ''over fertilization would not cause it as far as I know. Other than the flowers, the Astrophytum for example, seems perfectly normal and does not show signs of being over fed.
As for the stone eaters article, I don't think the author has given much consideration to the fact that cacti in the habitat are not confined to a pot but are free to form extensive root systems to find nutrients they require. In natural systems, as a nutrient is removed by the plant it will get replaced. It should be remembered that the almost limitless surface area surrounding the plants will gather many nutrients during rain and re-charge what has been taken by the plant roots. That's why plants in the habitat can continue to grow well (given enough water). Nutrients move around a lot in nature but they are sooner or later depleted in pots unless we add more of them. If you imagine a cactus growing out of crack in what seems to be solid rock, you need to take the whole hill or mountain into consideration and realize that when it rains, water rich in dissolved nutrients will be channeled into these cracks. So the plants end up seeing nutrients from far and wide and not just the rocks they are attached to.
Another way nutrients reach the plants .... After rain the soil water begins to evaporate from the surface. As it does it draws up more water via surface tension from further down and brings dissolved nutrients with it. The nutrients remain where the water turns into vapor and leaves the surface. None of this happens in a pot full of rocks.
Also, no mention is made of the possibility of nitrogen fixation by bacteria living around the roots. (However I did not read it intensively). The plants are getting their N from somewhere and it's not from solid rocks. Thunderstorms also play a part.
The phosphorus question. No one knows what the affect of too much P on cacti looks like. The only way to know is to do a trial with blocks of identical seedlings and give each block ever increasing concentrations of P. But it would probably turn out to be rather pointless because we already know that we should not give too much P from the results of other trials for other plants. So why do it in the first place? The trial for African violets showed flowering decreasing by 50% when the N/P ratio was increased from 0.14 to 0.44. If we stick to somewhere around 0.25 to 0.35 more or less, there will be no problems.