Turface vs Pumice vs Crushed Limestone

[MitchellM]

I'm trying to grow Pediocactus simpsonii, Escobaria Vivipara and Ariocarpus fissuratus from seed.

I have found a source of turface where I live, I can get pumice by mail order, and I can probably talk a landscaping stone vendor into selling me less than a dump truck load of crushed limestone. Perlite is easy to get but I dislike working with it.

What is my best choice for the desert and mountain cacti?

[Pereskiopsisdotcom]

You want something that is not a total pain in the butt for you to get and gives you drainage. No more and no less. If it looks cool and is reasonably pricey that's a bonus. I originally fell for the fallacy that the more stuff in my homemade soil the better it is. The reality is it needs to give you the proper drainage for your watering. You want to test it by mixing various quantities of the soil ingredients you get in your containers without any cacti and watering them. Pay attention to how quickly the water escapes the container and how many days it takes for the soil to be dry to the touch. Take notes and photos from your phone if you can to help you remember. It's different for everyone based on our own local climate, humidity, indoor/outdoor, season, lighting/sun, etc.

Depending on which type of Turface you are using or a different imitative brand may or may not have harmful additives. I use a fire-baked clay cat litter (non-clumping and scent-free) and it achieves nearly the same result. It's also dirt cheap! I do not have economic access to pumice (outside of the United States) so I use diatomaceous earth marketed as floor dry. I would definitely use pumice if I had reasonable access. I also use granite grit instead of crushed limestone now because it holds up long term and a lot of crushed limestone is made to act as a packing agent in construction and will thus impede drainage. And historically I've used coconut coir because it really inhibits rot and dries out quickly. Recently though I've been swapping it with just regular garden soil because I've gotten the hang of things (watering frequency and stronger lighting). So for me, it might look like 40% diatomaceous earth, 30% fired clay, 20% plain garden soil (sifted to remove clumps), and 10% granite grit. Everyone who replies will have a different recipe that works for them.

When you're getting started learning about putting together a soil I think the biggest mistake you can make is that thinking sand or smaller particles like sand (classic desert) are the ingredients to a cactus soil. From my experience, using larger particles and a mixed variety of sizes and shapes of particles really makes a difference in drainage, root growth, and success. With that in mind, take out huge clumps and sift out the dust.

And as an aside, for seedlings, I have seen people use store-bought cactus soil bags to germinate seeds no problem. They mostly need consistent moisture and heat to get going. I use my mix for seedlings as well but not as picky.

[Kenizona]

I like to collect buckets of coarse river sand, and then sift it through window screen to remove the fine parts. If needed, I'll sift it again through a 3/16 screen to remove the larger gravel (which goes into a potting mix for larger plants). This produces a coarse grit that works very well as the basis for a seedling mix. I just add some oil-dry (similar to turface) and a little organic material such as bagged cactus mix with the large bits sifted out. The pumice I can get here is too coarse for seedlings, but works great for larger plants. I don't use limestone in potting mixes even for plants which naturally grow in it. They can tolerate it better than other species, but I have not seen evidence that they actually need it. For the species you listed I would recommend using only a little organic material, and avoiding peat. Good luck!

[keith]

Turface and pumice should work well. Limestone might work also not sure ? For seeds I use a smaller size pumice like dry stall. I use pumice because I know where to get it close by which is convenient. I found turface one time it was dumped from a local baseball field it worked well but hard to find around here and I had to shift it as it was mostly sand sized which is too small. Limestone rocks I don't know where to get and they would have to be small like 1/8' gravel.

[samhain]

I’ve had amazing rooting in pumice, but swapped to fired clay(oil dry product). 40lbs costs less than 5lbs of pumice

[wilsontucker]

another option is pea gravel (or screenings) which is just small pebbles rocks. Can get at most big box stores 50lbs for $3-4

[dwood5513]

I feel like pumice retains too much moisture. Ive lost a few fat root specimens in pure pumice. I use 1:1 sterilized sifted garden soil:floor dry for seedlings 2:8 (soil:floor dry) for most mature plants, 1:9 for tap root plants. Half half seems high but have found sterilized with some sand on top that i get better growth. Also hydrogen peroxide mist keeps moss down, but doesnt eradicate it once it forms. Floor dry is cheaper than garden soil $10 for 30 lb bag, around here pumice is even cheaper $7 for 30 lb bag, i have no idea what turface is ive never seen it here.

[7george]

Exclude limestone rocks right away. "Too much moisture" is good for seedlings during first months. Do not try to find an ideal material that will work for seedlings and adult plants. Turface is maybe best from listed above. Start with small-sized fraction comparable with seeds' size.

I usually do a mix of 3: Zeolite, vermiculite and sand. But this is for growing seedlings in bags indoors. For outdoors and different climates the substrate can vary.

[MitchellM]

There was a mix called "Nan's Mix" a lot of trichocereus growers liked that was 1 part composted manure, 1 part bagged topsoil and 1 part limestone graveI. That's what made me think limestone. Others say limestone is bad for container plants even if they are in limestone soils in the wild. I decided to try Black Gold Cactus Mix with added perlite for my seedlings since I already have some. I've heard clay is good in soils because it has a lot of sites for ion exchange. I wonder if that's also true of Turface and Napa oil dry. I'm looking at one of those mixed with a compost based potting mix made by Purple Cow once I move to bigger containers. Thanks everyone for good suggestions.