Since the Arizona Snowcap dislikes standing water, it should be planted in a light, fast-draining cactus mix. The soil may also have 70-80% mineral grit like perlite or pumice for improved drainage. If planting the cactus in a pot, make sure that it has large draining holes to again encourage drainage.
Beside this, how do you take care of a thimble cactus?
Water thimble cactus sparingly during the summer. Throughout the winter months, water only if the cactus looks wilted. Always allow the soil to dry between each watering. The cactus is likely to rot very quickly in soggy soil.