Sowing Seed in Pure Mineral Mix

[zpeckler]

Hey guys,

I'm starting to think ahead towards sowing my third round of cacti seeds next spring, and I'm wondering if anyone has experience sowing seeds in a pure mineral mix? I've got some seeds from some species that are reputed to be very rot-prone (Echinomastus johnsonii and a few other Echinomastus species, Escobaria alversonii, Echinocactus polycephalus, etc) and I'm wondering if decreasing the organics they they're sown in might increase seedling survival?

I've got access Turface, fine pumice, coarse construction sand, and fine scoria. All of which feels like a small enough particle size for seedling roots to do well in.

One of the subtexts to this question is my frustrating experience with using sphagnum peet moss as a major component in my seedling mix from last spring. I've had good results with seedling survival in this mix, but it's such a pain to get it re-wetted after it dries out.

With that in mind, if an organic component to a seedling mix is still recommended, is there a better organic medium than sphagnum?

Thanks as always,
Zac

[FredBW]

Can't answer about pure mineral mix. But as far as a substitute for peat. Co Co Coir works for me. There are those here that will tell you to "avoid it like the plague". But I use an awful lot of it.
The way I use it for seedlings is I put a layer in the bottom of the pot. No matter what I am using above it. The reason I do that is I bottom water all seedlings on a wicking mat. The coir readily absorbs water off of the mat,and gets the siphon going to dampen what ever medium you use. Would probably moisten Turface and sand that way. But probably not so much on grittier stuff.
Coir doesn't repel water like dried out sphagnum. Most of the things I have layered coir on the bottom like that,roots are drawn to it like a magnet.
Astrophytum and Copiapoa are probably the most rot prone seedlings I have grown this way. Going on year 2 anyway.
I have a lot of succulents like Jade I have started and grown in 100% coir

[keith]

is there a better organic medium than sphagnum? "

I use sandy desert soil at about 20% volume for cactus and 30% for mesembs.

[Tom in Tucson]

Just some advise for what works for me ATM.

It's nearly impossible to make a 100% pure mineral mix. If I achieve 95% or better, I'm satisfied. It should be obvious that I don't purposely add any organic material, unless I'm trying to improve moisture retention. (like some plants that do better in it).

The mineral soil I use for "difficult" species, is the same that I use as a substrate for starting almost all of my cactus seed . There are exceptions, (as there always are), but not worth mentioning.

One easy question: Where the h**l did you find the Escobaria alversonii seed?

[zpeckler]

Where the h**l did you find the Escobaria alversonii seed?

Hey Tom!

Aiko has been posting links to seed lists over in the General board, and these guys had the E. alversonii.

https://www.cactus-hobby.eu/en/cactus-hobby-en/

They also have E. viviparia var. desertii if you're into both the SoCal Mojave Escobarias. Both are listed under Coryphantha as the genus on the seed list; it's beyond the scope of my taxonomic knowledge to say whether Escobaria or Coryphantha is more correct, but more books and stuff I've seen list both species as Escobaria so that's what I go with.

[SDK1]

I'm a convert to MikeInOz's recommendation to use finished compost as the organic portion in amy seedling mixes. I've used pine bark fines too and they work well for me. They seem to rewet more easily than peat but not quite as easily as coco coir. Finished compost seems to rewet a bit easier than peat in my experience. My problem is being forgetful/busy and letting the pot dry out in the first place which I try to avoid. If I let that happen I usually have to set all the pots in a tray and let them soak for a few hours, regardless of the organic component I use.

Frankly, after about 3-6 months I have to soak them like this if I let them dry. Inorganic or not, the fine particled seedling mix forms a bit of a crust so top watering takes longer and is annoying. Makes me try a bit harder to keep them pretty well-watered to avoid having to soak them to rewet the mix.

[Tom in Tucson]

Where the h**l did you find the Escobaria alversonii seed?

Hey Tom!

Aiko has been posting links to seed lists over in the General board, and these guys had the E. alversonii.

https://www.cactus-hobby.eu/en/cactus-hobby-en/

They also have E. viviparia var. desertii if you're into both the SoCal Mojave Escobarias. Both are listed under Coryphantha as the genus on the seed list; it's beyond the scope of my taxonomic knowledge to say whether Escobaria or Coryphantha is more correct, but more books and stuff I've seen list both species as Escobaria so that's what I go with.

Thanks for supplying your source for the Escobaria alversonii seed. Ever since I've had a couple seed orders confiscated, I very rarely order from abroad. When I do, I usually go through the USDA rigmarole.

Ever since Steven Brack stopped running Mesa Garden (2016), SB1800 has only been offered 5 times, and always sold out within a couple days. The last time I was able to order from them, was almost exactly 2 years ago. At that time you could only order 2 packets, and even if their stock had still been available, you usually can't order again for a month. Needless to say, these seeds were doled out to a number of 2" pots, and given my highest level of TLC. So far so good. My yield thus far has been 80-90^% (fingers crossed, and knock on wood). Just a word "to the wise", treat these like you are growing Homalocephala polycephalus.

BTW, Escobaria desertiii is almost too easy to grow from seed. I've got more than I will ever need, but I do enjoy watching these little white bristly balls grow.

[zpeckler]

Thanks for the replies, everyone.

From what I see on the forums it sounds like most people use some organic portion their seedling mixes. It also seems like there are as many opinions on what that organic component as there are growers! I'll try to figure out something I can get locally that compromises between the suggestions I see here on this thread and elsewhere in the seed-growing posts.

Anyone have any thoughts on how much of a seedling mix should be organic? I used 50% peat moss for my current seedlings, and it seems like that's clearly way too much. I'm thinking somewhere on the order of 15-25% would be a little better?

[zpeckler]

Ever since Steven Brack stopped running Mesa Garden (2016), SB1800 has only been offered 5 times, and always sold out within a couple days. The last time I was able to order from them, was almost exactly 2 years ago. At that time you could only order 2 packets, and even if their stock had still been available, you usually can't order again for a month. Needless to say, these seeds were doled out to a number of 2" pots, and given my highest level of TLC. So far so good. My yield thus far has been 80-90^% (fingers crossed, and knock on wood). Just a word "to the wise", treat these like you are growing Homalocephala polycephalus.

Thanks for the heads up. I'm still figuring out how to grow E./H. poly so it'll be a learning process. I spent a ton of time scouring seed sellers to get a bunch of both E./H. poly ssp. polycephalus and E./H. poly ssp. xeranthemoides, and I sowed enough that even with the low germination rate I have about 45 seedlings. So far so good, although I'm starting to think I might need to transplant them into a mineral mix as I've noticed a few white flecks on the surface of the medium that are making me concerned for fungus growth. That's a story for another post, though. I'm hoping that I have enough of the seedlings survive that I can try transplanting them into different mediums, and then try summer watering some and winter watering others. That's a long way away, though. First they gotta survive.

[Hanazono]

G'morning zpeckler,

I'm thinking somewhere on the order of 15-25% would be a little better?

Since seedlings are kept in the same pot for one year at least, I mix 25% of organic material in my seed-rising mix.

Frank

[7george]

If in the water before and after the germination is added some fertiliser seedlings can grow during at least 6 months or the whole first season in inorganic mix. These below are 2 - 3 months old in a mix of perlite, vermiculite and sand. A modification of "jar method" under daylights with some sunshine occasionally.

SAM_995sdl.JPG (161.41 KiB) Viewed 8959 times

No need to re-pot if you do not want, just uncover or take the pot out when their size looks adequate.