I live in an area (Delhi, India) where sterilised potting mixes are unavailable. And potting mixes are expensive. So I prepare my own usually. I want to prepare potting soil for planting roselle and lettuce separately. I have the following things with me- Cocopeat, Vermicompost, Bagasse compost, Neem kernel meal, Mustard meal, Perlite (mostly powdered) and Vermiculite. I also have soil used previously. But I avoid it because it is difficult to move the container and it becomes prone to disease and other problems. So is there any general ratio I can follow for the ingredients for these plants?