watering & fertilizing for mineral soil mix

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
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MikeInOz
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Location: Sth east Australia

Re: watering & fertilizing for mineral soil mix

Post by MikeInOz »

Steve Johnson wrote: Sat Sep 25, 2021 10:16 pm The only thing I'm concerned about is the fact that you have the same amount of N and Ca (even though your Ca-to-Mg ratio is good), seems like the Ca would be too high in relation to N.
As long as it doesn't interfere with pH, (nutrient uptake), calcium is not a problem. There's no such thing as Ca toxicity.
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Steve Johnson
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Location: Los Angeles, CA (Zone 10b)

Re: watering & fertilizing for mineral soil mix

Post by Steve Johnson »

4d3d3d3 wrote: Sun Sep 26, 2021 1:20 am...but I did buy a bottle of Dyna Gro once that was already crashed out (maybe it froze in storage?).
Re. Dyna-Gro ferts "crashing out", I can describe it more specifically...

When they're allowed to freeze, the Potassium salts precipitate out and crystalize. In my part of L.A., overnight lows during winter usually don't go much below the low 40s. However, there was one winter (think it was 7 or 8 years ago) when a cold snap took it down to about 35 for a couple of nights. I kept the 7-7-7 in a backyard garden shed, and when I brought it out, the jug sounded like it was filled with gravel. According to directions on the Dyna-Gro label, the only way to bring the crystals back into solution is by diluting the unused portion with an equal amount of hot water. That's what I did, although it means diluting 1 tsp. per gallon of water as opposed to the 1/2 tsp. per gallon I was diluting before that unusually cold winter. I've been keeping it under the kitchen sink in my apartment ever since.

I'm down to a quart of the 7-7-7 jug I bought in 2012, but I read your response and what you said about your General Hydroponics ferts with more than a little interest. Such being the case, that quart of 7-7-7 may go bye-bye as I switch over to those ferts starting with the 2022 growing season. Out of the 68 cacti I have in my collection, I'm growing 65 in a soil-less pumice and granite gravel mix. Pumice and granite have a CEC of pretty much zero (why I need to fertilize every time I water), so Mike recommended that I add 10% zeolite to give the mix a little CEC "oomph", which I'll do as I repot everything early next spring. 2% Ca and 0.5% Mg in the 7-7-7 is pretty good, and my original thought before we had this discussion was to double it with a Cal-Mag fert. As I've been writing here, I just saw the following response from Mike:
MikeInOz wrote: Sun Sep 26, 2021 2:48 am
Steve Johnson wrote: Sat Sep 25, 2021 10:16 pm The only thing I'm concerned about is the fact that you have the same amount of N and Ca (even though your Ca-to-Mg ratio is good), seems like the Ca would be too high in relation to N.
As long as it doesn't interfere with pH, (nutrient uptake), calcium is not a problem. There's no such thing as Ca toxicity.

Yeah, those General Hydroponics ferts of yours are looking better and better. Unfortunately storing rainwater is out of the question for me (SoCal's "rainy" seasons are too unreliable anyway), so I have to rely on acidifying tap water with 5% white vinegar. Without going into a lot of detail about my procedure for doing it, I'll just say that my acidified watering solution is in the pH 5.0-5.5 range. The pH does rebound up to 7 by the time the mix dries out, although I now have to wonder if I've been acidifying a little too much. I dunno, maybe it should start out more like 6? Anyway, you and Mike have been really helpful, so I think it'll be time to up my growing game based on everything I've learned thus far.

Note to ohugal -- I hope this is giving you some useful ideas! :)
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My location: Los Angeles, CA (Zone 10b)
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