Well, I guess there is root bound. And there is really root bound.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm I have a Mammillaria crucigera that needed a bigger pot in April 2015, so here's what came out of its potful of soil-less mix:
If they are so important I am indeed wondering why they are not included. But also, are they really that important given that specialist cactus nursery don't include them? (To be fair though to Kakteen Matk here in Berlin: they are actually not producing this product but are reselling it. I just named it that way since I bought it there.)Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm No worries. And no disrespect to Kakteen, but you might want to ask them about why they don't have any Ca, Mg, or S in their fertilizer.
I made my own calculator. And found two mixture which get even closer to your suggested ideal ratio.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm If this isn't possible for you, I wouldn't give up on the Kakteen Matk and Neudorf Schachtelhalmloesung ferts (must be in combination for better NPK balance -- I believe Jerry's calculated dilutions apply to the combo).
I actually have a hydroponics/"growth" shop in my neighbourhood. They offer a Ca/Mg supplement but it doesn't state the ratio online. I'll check it out.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm You can address the lack of Calcium and Magnesium with a Cal-Mag fertilizer supplement.
Yes, makes sense.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm I'll recommend that you alternate between the NPK and Cal-Mag -- fertilize with the NPK ferts, fertilize with the Cal-Mag fert in the next watering, go back to the NPK ferts with the watering after that, and so on. (Am I making any sense?)
As mentioned, after giving the pots a bottom soak I place them on paper towels to drain the excess water at the bottom of the pot. And the bottom of the root ball yesterday was very dry after watering it one week earlier. In reasonable warm temperatures und with sunny days (indoor SE window sill with fan) these small pots dry out in 3-4 days with this soil mixture. To monitor this, I weigh the pots before and after watering and then weekly. The larger pots I water every 2 - 3 weeks.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm By the way, if your mix leaves any moisture at the bottom of the pot whenever you water, I'd also recommend that you water a little less frequently.
Understood.Steve Johnson wrote: ↑Sun Aug 15, 2021 11:47 pm by a nugget of wisdom about how to approach watering -- when in doubt, don't.
Best.