Soil making!

[Okiram]

Also, does anyone here have a favorite potting soil they use or make, that you can recommend?!?
I would actually like to make my own. But being a "struggling artist", I usually use soil from around the yard or vacant lot or something I have been told that this is not a good way to go about it as the soil could harbor pests and disease. I haven't really had too many issues with this but, it's not the most attractive. In a different world where I have lots of money and own my own place, I would have sacks of all the components needed to mix up whatever soil is required for the specific plant in mind!
Let's pretend that is the world we live in currently! With this in mind, what soil mixes do you all swear by? What soil mix would you recommend for agaves in Tucson? Aloes in Tucson? From Madagascar? From South Africa? Or just a good all arounder?
Thanks for your time and help guys! I'm so glad I stumbled across this forum!

[edds]

I'm currently experimenting with potting mixes a little bit. I have a supply of decent soil that has been enriched and had added multipurpose compost (peat or peat substitutes). I'm currently mixing this with a very peaty brand of John Innes that dried too fast for me used on its own and mixing this about 60:40 with potting grit.

My hope is I can move to using sharp sand and peat-free compost I am making myself (from shredded conifers) to replace the not-very-good John Innes once the shreddings have rotted down enough.

[mcvansoest]

I think the first thing you should try and find is a good local supply of pumice. Maybe the Tucson Cactus and Succulent Society has some for its members (the C&S S over here does). If you have good pumice in a variety of sizes I'd say that is most if not all of the battle won. I usually mix pumice with a store bought cactus and succulent mix. I used to not care too much what was in it, but more recently I have gotten slightly fancier stuff as it has turned out to be more consistent in the size and nature of its components.

I mix that in different proportions with the pumice and that is for my potting mix.

I do not amend the soil for plants I plant in the ground, simply too much hassle and unless you do a really good job grading from your custom mix to whatever the local soil is could actually be more of a detriment than an advantage.

As to using local soil for your potted plants. The only thing I'd worry about is the clay content if it is nice pretty coarse well draining soil (in my experience with the local soils here in the Phoenix area that is pretty doubtful) I see not much harm in using it, but if it is very clayey and becomes a solid hard to break up clump when it dries out, I'd shy away from using it without mixing it thoroughly with something very coarse.

[westfork]

We use gravel and pumice (both in the 1/4" - 3/8" range) blended with a general potting soil that is not too peaty and some stringy coir and some slow release fertilizer. The mix is adjusted according to the plants. In this area Black Gold seems to be a pretty good potting soil at a decent price. The gravel and pumice make up from 50% to 80% of the mix, depending upon the plant and the watering schedule. This added mineral content is as low as 1/3 of the mix for non xeric plants like palms, manfreda, and semps. I have tried to like cactus mixes but prefer larger aggregates to all the fine sand they seem to contain.
I screen the pea gravel to two sizes depending upon the type and size of plant. The fifty pound bags of this from the farm supply or big box store yield about two thirds gravel just below 1/4" and the other third of up to 3/8" size. The weight of the gravel helps keep pots from blowing away during high winds:

potting soil materials

M3IMG_4898 sm 8-26-2023.jpg (341.16 KiB) Viewed 3081 times

and a high mineral blend of these used for cactus:

soil mix for cactus

M3IMG_4904 sm 8-26-2023.jpg (204.46 KiB) Viewed 3081 times

[Samhain]

I use fired clay, a lot cheaper than pumice. Tractor supplies oil dry does it for me. Rinse and Mix that at different rates with whatever omri soil I have around, often kellogs. My cacti are often 50% or more the fired clay, agaves seem to like a bit more soil for water retention. I try to stay away from peat, becomes hydrophobic when it dries out and I let everything thoroughly dry out.

[Gafoto]

Fortunately there are a lot of Tucson growers on this forum who can tell you what they use for succulents! I was honestly surprised with how coarse the soil was of all the plants I purchased in Tucson. Very sandy and rocky with minimal organic material.

Here in Salt Lake I use a roughly 60:40 milled coco coir : pumice mix. This works for Agave of all ages, I start seeds in it as well. Perlite is more of a hassle than it’s worth.

[Fairview]

I use fired clay, a lot cheaper than pumice. Tractor supplies oil dry does it for me. Rinse and Mix that at different rates with whatever omri soil I have around, often kellogs. My cacti are often 50% or more the fired clay, agaves seem to like a bit more soil for water retention. I try to stay away from peat, becomes hydrophobic when it dries out and I let everything thoroughly dry out.

The oil dry is clay. Perhaps I'm looking at the wrong item. How does adding clay help with drainage? I'm getting ready to make a raised bed and looking for inexpensive stuff to use.

[Samhain]

I use fired clay, a lot cheaper than pumice. Tractor supplies oil dry does it for me. Rinse and Mix that at different rates with whatever omri soil I have around, often kellogs. My cacti are often 50% or more the fired clay, agaves seem to like a bit more soil for water retention. I try to stay away from peat, becomes hydrophobic when it dries out and I let everything thoroughly dry out.

The oil dry is clay. Perhaps I'm looking at the wrong item. How does adding clay help with drainage? I'm getting ready to make a raised bed and looking for inexpensive stuff to use.

It is calcined or fired clay. It doesn’t do much if any water retention, essentially doesn’t break down, isn’t as heavy as some grits that cause compaction and doesn’t float out like perlite. Very popular with cacti as well as bonsai.

[Fairview]

I use fired clay, a lot cheaper than pumice. Tractor supplies oil dry does it for me. Rinse and Mix that at different rates with whatever omri soil I have around, often kellogs. My cacti are often 50% or more the fired clay, agaves seem to like a bit more soil for water retention. I try to stay away from peat, becomes hydrophobic when it dries out and I let everything thoroughly dry out.

The oil dry is clay. Perhaps I'm looking at the wrong item. How does adding clay help with drainage? I'm getting ready to make a raised bed and looking for inexpensive stuff to use.

It is calcined or fired clay. It doesn’t do much if any water retention, essentially doesn’t break down, isn’t as heavy as some grits that cause compaction and doesn’t float out like perlite. Very popular with cacti as well as bonsai.

The oil dry sold by my local TS is labeled as montmorillonite clay. This clay is highly absorbent and among its other uses, is used to improve water retention in soils. Arcillite is calcined montmorillonite and it does not retain water. If oil dry wasn't absorbent it wouldn't be much good to clean up spills. Can you post a link or pic of what you use?

[Gafoto]

Bonsai Jack sells that kind of clay as a soil amendment. I have never tried it but now I’m curious. Apparently it swells up quite a bit when wet. This seems like it might be an issue in a clay pot?

[Paul S]

I've been using something called moler clay for my potted cacti and succulents for 15 years or more. It was used initially by bonzai growers here but has migrated to cactus and succulent growers. We can buy it as either a type of cat litter or, more usually, a petrol forecourt spills product. I tend to either use it on its own or blended with up to around 30% planting compost (these days coco fibre) depending upon a random notion I might have about the individual plant's organic material requirements. But it is great for rooting cuttings.

In my 'just frost-free' greenhouse I have raised planting beds for my slightly more tender cacti and succulents. These beds are filled with LECA, which is Lightweight Expanded Clay Aggregate. No organics, just the LECA. I give a liquid feed once in a while when watering. The plants do very well grown hard like this.

[cerg]

Dear all,

For Aloe, we use the following:

1) 25% river sand (including the fine component) (if we do not have this, the fine fraction of volcanic lapil)
2) 25% sieved loamy soil from the garden (or universal soil)
3) 50% river gravel (if we do not have any, then 3/5 volcanic lapil)

You need to fertilise regularly, but it seems to work well with Aloe and most cacti. In those cases where you need Ca in the compost, we add carrara marble gravel / grit (which is a side product of carrara marble extraction and cutting).

Only problems 1) this substrate is quite heavy 2) it requires regular fertilising.

Kind Regards
Corrado

[Viegener]

I usually mix my own soil in small batches depending on which xerophytes I'm working with. I learned what kind of soil cacti, agave, aloes, and soft succulents like best. They all want really good draining soil in different degrees; some like a little organic matter, some do not. Understanding the difference between organic and mineral growing mediums is essential.

I always have perlite, coconut coir, pumice, and ordinary cheap potting soil on hand. I like coir better than anything like peat moss or potting soil for the organic component. What it is really good for is holding a little moisture and unlike peat moss, potting soil, etc, it rehydrates easily when it is bone dry (this is a real advantage when you're growing in pots.

When I had less money to spend, I used decomposed granite (very good, lots of it in desert areas), sand (river or stream bed not beach sand), pebbles, and my own compost. These are easy to find & the only hard part is schlepping them home.

If you're on budget and can go dig up most of what you need, coconut coir is the first thing I'd buy. You'll find it at any hydroponic store (which mainly supply home marijuana growers) in 12lb compressed bricks. A little goes a long way.

Always avoid peat moss for xerophytes, and never use pure "potting soil" or soil "amendment". Most of it these days is made with processed sewage sludge and ground up wood products. Once they break down they turn into black sludge that only swamp-growing plants will thrive in.

The cheapest place I've found for all this stuff is landscape suppliers - one in the Los Angeles area is Whittier Fertilizer. You can check out the prices & selection. Much better than Home Depot or Lowes...