Although potted plants don't dry up without vermiculite, this substance does help soil to retain moisture. There are other substances that can be used in potting soil in place of vermiculite, such as perlite, styrofoam and peat moss.
Vermiculite is a volcanic mineral often used in potting mediums because it absorbs soil and fertilizer, keeping soil moist and rich in nutrients. It also helps to aerate soil, ensuring that it is well-drained. This mineral easily absorbs certain nutrients, such as calcium, magnesium, potassium and ammonium, which are necessary to the growth of plants. It also encourages seeds to germinate more quickly than in regular soil.