What type of soil is best to use when starting Osteospermum from seeds?
Certified GKH Gardening Expert
Any good standard potting mix will usually be sufficient. You may also choose a soilless potting mix. Here is more info: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soilless-growing-mediums.htm
I shall make the assumption that you're starting your seeds indoors. Use any good seed-starting mix. This article has more information about these lovely plants: https://www.gardeningknowhow.com/ornamental/flowers/african-daisy/african-daisies-osteospermum.htm