And as this is a Science Fair project for you to research and experiment to answer the question "What material grows the best plants?", we can only make some suggestions and offer guide lines, not give you answers.
I would suggest you narrow down your queston and choose a plant, i.e. "what is the best soil for tomato production?". Or "what fertilizer works best for cucumbers?". Remember to keep all other variables the same.
1. Ask a question
2. Research the question
3. Formulate a hypothesis
4. Test your hypothesis
5. Analyze your data
6. Draw your conclusion
7. Win First Place in Science Fair