My main collection is Astrophytum asterias. I sow seeds every year.
Although I use heating pads for cactus seed germination, a simple wet-box is used for asterias germination. I have recognized seedlings germinated by a natural condition are robuster then that of heating pad. I sow seeds in mid of November and it is a bit early to prepare but the repotting of seedlings sown seeds last year is in progress.
I have repotted 3100 seedlings in total including 1200 asterias. I got several good pottingmix samples in this year and tried them.
1. Asterias cv miracle kabuto, sown seeds 15/11/2011, before repotting
2. Repotted miracle kabuto, 25 seedlings in 10 cm square pot
3. Miracle kabutos with shifted pumice sand
4. Miracle kabutos with original size of pumice sand, 1-7 mm
5. Miracle kabutos with shifted scoria
6. Super kabutos with my original pottingmix, organic material plus zeolite and scoria