Then, what can I use if I don’t have succulent soil?
The best mixing ratio of the three ingredients is two parts sand, two parts gardening soil, and one-part perlite or pumice. Translating this to cups makes it 3 cups of sand, 3 cups of soil, and 1.5 cups of perlite or pumice. The purpose of pumice or perlite is to aid in aeration and drainage.
Secondly, can I use Miracle Gro potting mix for succulents?
Plant succulents in containers using Miracle-Gro® Cactus, Palm & Citrus Potting Mix. Plant outdoor succulents during the spring and summer. Plant indoor succulents anytime. Water plants at the time of planting and again whenever the top 3 inches of soil are dry.