Vermiculite is a natural mineral. It starts off like mica–sort of a flaky rock. When heat is applied, it expands and becomes a light, fluffy, fire-resistant material. There are numerous uses for this product (like insulation), but here we’re using it as a soil conditioner for our garden beds. It helps keep soil light, allows for good airflow, and absorbs and retains water. If you simply cannot find vermiculite, you have an alternative. First, you can always garden with straight compost, or a mix of compost and peat moss. My experience is, this soil gets very bogged down with water, and doesn’t drain well. The other option is to purchase Perlite. This is the white stuff you find in potting mixes. It does not have all the great benefits of vermiculite, but will do in a pinch.