Cacti Soil Mix Question 2

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JCcares
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Cacti Soil Mix Question 2

Post by JCcares »

After waiting 8 days I just watered my newly potted cacti.

The small pots I circled around 2oz of rain water.

Within 10 seconds the rain water started dripping out the bottom of all 8 newly potted plants.

My question is did I make the correct is my soil the right potted soil?

See images

I used one scoop of the “Black gold organic soil“ and just a little less of a scoop of “Pumice” and mixed it together well. That is it.

Thank you for all your help!
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greenknight
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Re: Cacti Soil Mix Question 2

Post by greenknight »

That mix should be okay for Echinopsis. Unfortunate that they use the same label for different formulations, so it's not clear exactly what's in the bag you bought. Your final mix looks plenty gritty, though.

I doubt this is a case of peat not absorbing water - that happens only when it's bone dry, and bagged potting mix is generally damp. Even after 8 days it shouldn't be that dry.

If the mix is holding that little water, you probably won't have problems with it staying too wet once the roots have developed. You may find you need to water pretty often, but that's better than having them stay too wet.

Watch them closely now, see if the are taking up the water quickly. You could, after a few days, set one of the small ones on a paper towel and see if it draws any water out of it. If it does, that means the mix in the bottom of the pot is still saturated, in that case it would be a good idea to use towels to draw the excess water out of all of them.
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JCcares
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Re: Cacti Soil Mix Question 2

Post by JCcares »

greenknight wrote: Thu Jun 16, 2022 7:29 am That mix should be okay for Echinopsis. Unfortunate that they use the same label for different formulations, so it's not clear exactly what's in the bag you bought. Your final mix looks plenty gritty, though.

I doubt this is a case of peat not absorbing water - that happens only when it's bone dry, and bagged potting mix is generally damp. Even after 8 days it shouldn't be that dry.

If the mix is holding that little water, you probably won't have problems with it staying too wet once the roots have developed. You may find you need to water pretty often, but that's better than having them stay too wet.

Watch them closely now, see if the are taking up the water quickly. You could, after a few days, set one of the small ones on a paper towel and see if it draws any water out of it. If it does, that means the mix in the bottom of the pot is still saturated, in that case it would be a good idea to use towels to draw the excess water out of all of them.

Thank you GreenKnight for coming to The rescue again!!

Sorry about my poor communication?

Teach me The accurate description of “gritty” please.

Here are some better pictures to communicate. I mixed one scoop of the store bought soil Black Gold and one scoop of the pumice. Actually a little bit less than a scoop of the pumice. Then just mixed it together like crazy.

Would it be best if I added LESS of the pumice?

Is the image that saids “finished soil“ gritty? That what gritty looks like and means? Do I want gritty?

THANK YOU sir!!!!!
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Steve Johnson
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Re: Cacti Soil Mix Question 2

Post by Steve Johnson »

The finished mix looks good to me, although Spence has experience with Echinopsis that I don't have, so he may recommend adding less pumice to the Black Gold product. What say you, Spence? :-k
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Re: Cacti Soil Mix Question 2

Post by greenknight »

That looks good for moisture-tolerant cacti like Echinopsis, I wouldn't change it. That Black Gold Succulent and Cactus looks better than a lot of commercial mixes I've seen, I can see why you went a little lighter on the pumice - good call.

"Gritty" means containing coarse mineral grains that hold little water so it drains freely. Pumice and perlite absorb some water, but they still enhance drainage - good enough for cacti like these, and for general-purpose potting mix (most commercial general-purpose mixes need more grit added for anything except swamp plants, not just for cacti). For plants adapted to extreme desert conditions, though, you need to use some non-porous grit so it dries even faster. I don't have experience growing in a humid climate like yours, I'd rely on the experience of those who do. I've seen claims that even straight pumice held too much water for some plants, which I find hard to fathom. :shock:

To amplify on my comment about how little water these pots retain - these are small pots for the size of the cacti, especially the three biggest ones. This was the right way to pot them, since the root systems were so small - but those big cuttings should fill those pots with roots quickly, and they'll dry out fast once they do. Probably will need bigger pots next spring.
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Re: Cacti Soil Mix Question 2

Post by JCcares »

greenknight wrote: Fri Jun 17, 2022 2:53 am That looks good for moisture-tolerant cacti like Echinopsis, I wouldn't change it. That Black Gold Succulent and Cactus looks better than a lot of commercial mixes I've seen, I can see why you went a little lighter on the pumice - good call.

"Gritty" means containing coarse mineral grains that hold little water so it drains freely. Pumice and perlite absorb some water, but they still enhance drainage - good enough for cacti like these, and for general-purpose potting mix (most commercial general-purpose mixes need more grit added for anything except swamp plants, not just for cacti). For plants adapted to extreme desert conditions, though, you need to use some non-porous grit so it dries even faster. I don't have experience growing in a humid climate like yours, I'd rely on the experience of those who do. I've seen claims that even straight pumice held too much water for some plants, which I find hard to fathom. :shock:

To amplify on my comment about how little water these pots retain - these are small pots for the size of the cacti, especially the three biggest ones. This was the right way to pot them, since the root systems were so small - but those big cuttings should fill those pots with roots quickly, and they'll dry out fast once they do. Probably will need bigger pots next spring.
Thank you Spencer you are truly the GreenKnight saving me from a lot of trial and error of mistakes. You have me on the right path now and I greatly appreciate all you easy to understand advice.

Today I did today I did weigh the eight pots like Steve said it will be interesting to me to see how much there weight will change in a few days.

Thank you again for ALL your help GreenKnight!!
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Re: Cacti Soil Mix Question 2

Post by greenknight »

You're welcome, and thanks for the compliments - I try to make things clear, glad you find it that way.

On the subject of grit, I should make it clear that the size makes a big difference. With non-porous grit, the spaces between the pieces are the only place water is retained - finer-grained stuff has more such spaces, so retains a little more water, With porous grit like pumice and perlite, you have that factor plus the finer grades have more surface area to absorb water.

Here, the Black Gold had a fair amount of grit, but it was fine stuff - the coarser pumice you added does more to improve drainage.

Also, I was wondering about the top dressing you used - what is that, aquarium gravel? Looks nice.
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Re: Cacti Soil Mix Question 2

Post by DWDogwood »

I use BG C&S mix as a 20% mix with the addition of pumice and Gold Fines from my rockery, which is decomposed granite (without the path hardener!!!!!). Then from the same rockery I put in a 10% scoop of sifted top soil- aka valley dirt.
(For certain things- Copiapoa cinerea for example- I use only the mineral components.)

I mistakenly got some BG general potting mix once but knew to relegate it to the tomato bed the second I opened the bag.

This is as decent a C&S mix as you can find in the stores.
Looks like your mix is great.
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Re: Cacti Soil Mix Question 2

Post by JCcares »

greenknight wrote: Fri Jun 17, 2022 4:09 am You're welcome, and thanks for the compliments - I try to make things clear, glad you find it that way.

On the subject of grit, I should make it clear that the size makes a big difference. With non-porous grit, the spaces between the pieces are the only place water is retained - finer-grained stuff has more such spaces, so retains a little more water, With porous grit like pumice and perlite, you have that factor plus the finer grades have more surface area to absorb water.

Here, the Black Gold had a fair amount of grit, but it was fine stuff - the coarser pumice you added does more to improve drainage.

Also, I was wondering about the top dressing you used - what is that, aquarium gravel? Looks nice.
I like the color of the green rocks
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Re: Cacti Soil Mix Question 2

Post by 7george »

If the potting mix retains less water then expected I'd recommend adding some vermiculite to it (~ 20%). This will keep it mineral and with good drainage.
If your cacti mess in your job just forget about the job.
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Re: Cacti Soil Mix Question 2

Post by greenknight »

JCcares wrote: Sat Jun 18, 2022 12:23 pm I like the color of the green rocks
Some people might think that was artificial - but, living in volcano country, I can assure you that all those colors occur naturally in lava rock.
7george wrote: Sat Jun 18, 2022 7:22 pm If the potting mix retains less water then expected I'd recommend adding some vermiculite to it (~ 20%). This will keep it mineral and with good drainage.
The problem with vermiculite is it breaks down more rapidly than the other mineral constituents, so you need to replace the soil more often.
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Re: Cacti Soil Mix Question 2

Post by 7george »

The problem with vermiculite is it breaks down more rapidly than the other mineral constituents, so you need to replace the soil more often.
That is true. Also the surface of the soil and cactus itself sinks down in the pot a bit. But regular soil change is a good thing. Japanese do it sometimes every year, can't we? :D 8)

Not sure that vermiculite brakes down but it compacts with the time. Because this commercial product has been expanded thermally.
If your cacti mess in your job just forget about the job.
°C = (°F - 32)/1.8
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