Pachypodium Baronii - soil

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astro_ian
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Pachypodium Baronii - soil

Post by astro_ian »

http://www.llifle.com/Encyclopedia/SUCC ... um_baronii

According to llifle.com Soil: Needs a gritty, porous cactus potting mix with peat gneiss sand, pH 4-5. It needs larger pot sizes than other species.

My question is how do I lower my soil PH. Do I add gypsum ? Does it matter if I don't follow the correct soil PH since I am already lowering the PH to PH 6 every time I water. if anyone can share their experience I would appreciate it.
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jerrytheplater
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Re: Pachypodium Baronii - soil

Post by jerrytheplater »

Gypsum is neutral regarding pH. It is Calcium sulfate. It is barely soluble.

Gneiss is a rock that is neutral. That is why it is recommended. So is Quartz/Silica. But, depending on where you live, that will determine what is available. Your local geology will determine what is available for you to use without paying very high transportation costs.

You need an acidic compound to lower your pH. Peat Moss will lower pH, make sure it does not contain limestone. You want pure Peat Moss, but not so much to hold too much water in your potting mix. Your water/fertilizer mix will usually be acidic. But, depending on where you live, your water could be alkaline.

I once bought some sand at a top soil distributor and didn't even think to test it for pH. I potted up some Venus Fly Traps which need very acidic low mineral potting mixes. They started showing signs of stress immediately. Turns out my sand was crushed limestone rock. I had to immediately repot. I now test the pH of sand before buying it in bulk. Take a small container, distilled water, and pH test strips with you. Put a layer of the sand in your container. Add water to fill and stir. Wait 5-10 minutes and stir again. Test pH. It should show up right away. Sand from the southern portion of my state is pure silica and its pH when unrinsed is between 4-5. If I rinse out the small amount of clay it contains, the pH will rise to about 6 or so.

Sulfur powder will also lower pH as it reacts with soil bacteria and forms sulfuric type acids. That is a very slow reaction. I use sulfur to acidify the soil under my blueberry plants, and other acid loving plants. Once per year application. Make sure you don't have any alkaline substances in your potting mix: limestone containing sand/gravel, phosphates can also raise pH. Also, watch out for peat potting mixes that contain limestone for pH adjust. You have to read your labels and understand them.
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.
nes
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Re: Pachypodium Baronii - soil

Post by nes »

jerrytheplater wrote: Tue Jun 07, 2022 12:25 pm Peat Moss will lower pH, make sure it does not contain limestone.
Nice take, learned a lot.
Curious as to what you think about using limey sands on Mexican cacti. Turbinicarpus, Arios, etc., species that grow in pure limestone rock/limestone soils.
Just recently I top dressed all my turbinicarpus and ariocarpus with calcareous sands with lots of fines. I felt they would like the limey soil collected above a weak limestone rock unit.
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jerrytheplater
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Re: Pachypodium Baronii - soil

Post by jerrytheplater »

nes wrote: Mon Jun 13, 2022 2:48 am
jerrytheplater wrote: Tue Jun 07, 2022 12:25 pm Peat Moss will lower pH, make sure it does not contain limestone.
Nice take, learned a lot.
Curious as to what you think about using limey sands on Mexican cacti. Turbinicarpus, Arios, etc., species that grow in pure limestone rock/limestone soils.
Just recently I top dressed all my turbinicarpus and ariocarpus with calcareous sands with lots of fines. I felt they would like the limey soil collected above a weak limestone rock unit.
I read somewhere on this site that those cacti that grow in limestone soil regions don't necessarily need the extra Calcium, they are just able to tolerate very high Calcium levels better than other cacti, and so thrive there. It was also pointed out that rainwater is acidic, (dissolved CO2 can drop the pH to 5.3. Even lower if there are acid aerosols in the air from air pollution/fossil fuel burning.), and since it is acidic, those cacti growing in limestone areas are able to tolerate their situation even better.

Now, I'd love it if someone will verify my memory as I don't remember where I read that.
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.
nes
Posts: 139
Joined: Wed Apr 14, 2021 5:46 pm
Location: Zone 10b

Re: Pachypodium Baronii - soil

Post by nes »

jerrytheplater wrote: Tue Jun 14, 2022 3:59 pm It was also pointed out that rainwater is acidic, (dissolved CO2 can drop the pH to 5.3.
That was one of the things I thought of. I don't remember where I heard that plants in general usually need acidic water. But I do recall hearing that a pH too high will cause the plant to not absorb any nutrients from the soil.
Then, when I started top dressing with calcereous soils I wondered if the limey soils would fizz too much and cause a calcium excess.
So far, they seem to be enjoying the top dressing, plump plants this summer.
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