Potting mix is best when it contains all the ingredients for the successful growth of your plants. Once you have decided the plants you like to grow, you can find out from your nursery on the type of potting mix you may need for success.
You can buy ready made potting mix from the nursery or garden center, or you can make your own potting mix to suit the requirements of your growing plants.
If you require plants to grow organic fruit and vegetables, then you will need a well drained soil, with organic compost to provide the nutrients for your plants. The compost will also help keep the water in the soil and maintain a pH level. You may need to find out the pH level in your soil, before you adjust the pH level in the compost.
You can buy a compost bin to create your own organic compost or you can buy ready made organic compost from your local nursery. A lot of people these days, like to create their own compost, and the nursery staff can give you advice on the best processes to create quality organic compost.