Are you growing your cacti in a soilless mix?

[jerrytheplater]

Are you thinking of using straight sand?

[GweenBean]

Are you thinking of using straight sand?

Not not necessarily, I'm open to pure or a mix but my main goal would be cheap and accessible mix. I've used all sorts of random mixes of coco coir, soil, turface and gravel in the past to my success.

[jerrytheplater]

Well, my memory was triggered. On Oct 11, 2022 I took a photo of one of my Leuchtenbergia plants which is mulched with 3/8" diameter plus rocks. When putting the photos on my computer I noticed a seedling growing at the base of one of those plants. I figured I'd let it grow becuse I didn't know what it was and I was curious. It didn't get any special care at all, just normal watering and fertilizing for the mature cactus. No special shade, no extra humidity, etc.

rsz 2022-10-11 E. cylindrifolia in L. principis pot a.jpg (106.51 KiB) Viewed 966 times

The next season I accidentally pulled that seedling out as an instinctive reaction to a weed. Once I pulled it out and saw the thickened root under the soil level I looked closer and realized I had a self sown Euphorbia cylindrifolia, or a hybrid which looks very much like E. cylindrifolia. Here it is on July 14, 2023 after I potted it up.

rsz 2023-7-14 E. cylindrifolia from L. principis po.jpg (115.79 KiB) Viewed 966 times

And here it is on Sept 20, 2023 after it started growing from the transplant shock.

rsz 2023-9-20 E. cylindrifolia from L. principis po.jpg (110.26 KiB) Viewed 966 times

And here is the most recent taken 11 months later on Aug 23, 2024:

rsz 2024-8-23 E. cylindrifolia in L. principis 3.jpg (72.69 KiB) Viewed 966 times

So I posted these photos to show it is possible to germinate seeds in a very coarse seedling mix. Don't ask me how the seed didn't get filtered down into that rock mulch. I would have assumed the watering and fertilizer would flush the seed down. I watered at times with the garden hose and was not gentle.

[GweenBean]

So I posted these photos to show it is possible to germinate seeds in a very coarse seedling mix. Don't ask me how the seed didn't get filtered down into that rock mulch. I would have assumed the watering and fertilizer would flush the seed down. I watered at times with the garden hose and was not gentle.

Interesting. I think Ive read that cacti seedlings grow in the shade of mother/mentor plants while they establish, guess something similar happened for that little euphorbia fella and it is impressive it didn'tt just disappear between the gravel.

I'm going to buy some granite grit, coarse sand and maybe pumice and see what pops up. I have tons of seed mixes to spear from over the years which i can haphazardly experiment with.

[7george]

Are you thinking of using straight sand?

Vermiculite is another option for seedlings.
All organic based mixes are not good for desert, slow-growing and rot-prone cacti.

[jerrytheplater]

I used about 25% Turface with maybe 20 Peat Moss and the rest gravel and sand when I made the mix for germinating Euphorbia tulearensis. That was a big mistake. I sowed about 22 seeds and got maybe 15 to germinate, which was good in my opinion. But they died off slowly and now I only have two left. Transplanted them out of that mix after 6 months. Fertilizer started after 3 months. They are almost two years old now, as they were sown on Jan 5, 2023 on a heat mat and LED lighting.