Garden soil and compost are both essential for growing healthy plants, but they serve different purposes and have different compositions. Garden soil is a natural or blended growing medium that typically includes topsoil, sand, silt, clay, and sometimes added organic material. It forms the structural base for planting and provides a balance of drainage and nutrient retention. Garden soils can be tailored for specific uses, like veggie beds, lawns, or native gardens.

Compost, by contrast, is decomposed organic matter—such as food scraps, grass clippings, and leaf litter—that's added to soil to enrich it with nutrients and improve its structure. Compost is not meant to be used alone in most planting situations because it lacks the density and mineral content of soil, but it's incredibly valuable as a soil conditioner. Together, soil and compost create an ideal environment for plant growth.

For most garden beds, a mulch layer of 5–10 cm (2–4 inches) is recommended. This is thick enough to block sunlight from reaching weeds, retain soil moisture and regulate soil temperature. Thinner layers may dry out too quickly or allow weeds to push through, while excessively thick mulch can restrict airflow and lead to root rot or fungus. Leave a small gap around plant stems and trunks to prevent mould and promote healthy airflow.

The best soil for raised garden beds is a well-balanced mix of topsoil, compost, and organic matter. This combination supports strong root growth, moisture retention, and nutrient availability—key factors for productive gardening. A common and effective blend is one-third topsoil, one-third compost, and one-third aeration material, such as coarse sand, coconut coir, or aged bark fines.

The topsoil provides structure and stability, the compost delivers essential nutrients, and the aeration component improves drainage and root health. It’s also worth tailoring your soil mix to the type of plants you're growing. For vegetables, a slightly richer compost mix works best. For native plants, a more free-draining, sandy mix with low phosphorus is often ideal.