Garden soil rarely performs well in containers. Potting soil is a specially formulated growing medium designed for plants in pots, troughs, and hanging baskets. It is usually sterile, free-draining, and light enough to allow roots to breathe while still holding adequate moisture.

Most mixes combine peat or coir with perlite, vermiculite, bark, and sometimes compost or slow-release fertilizer. The exact blend varies by purpose: seed-starting mixes are finer; mixes for mature plants may include more bark for structure. Unlike outdoor soil, potting mixes contain few weed seeds or pathogens when fresh.

Over time the organic components break down and the mix compacts. Repotting every year or two refreshes the medium and gives roots more room. Always choose a mix suited to the plants—cacti and orchids need specialized formulations. Good drainage holes in the container remain essential no matter how excellent the potting soil.

• Sterile medium for container-grown plants
• Light, free-draining, and moisture-retentive
• Usually based on peat, coir, or bark
• Needs periodic replacement as it breaks down