Miracle-Gro® Expand 'n Gro® Concentrated Planting Mix 0.67CFMiracle Gro Expand 'n Gro Concentrated Planting Mix is a great substitute for potting mix or garden soil as it can be used in ground or in containers. The compressed coir and plant food expands up to 3X when water is added and feeds plants for up to 6 months. It holds up to 50% more water than basic potting soil and creates up to 90% more air giving your plant's roots all the room they need to thrive.