How to Build Raised Garden Beds

Why Raised Beds

Raised beds solve several problems simultaneously: they bring the growing surface to a comfortable working height, completely bypass poor or compacted subsoil, drain freely, warm up faster in spring, and by never being walked on, maintain excellent soil structure indefinitely.

Materials

Untreated hardwood (spotted gum, ironbark) is durable and food-safe. Railway sleepers are popular but avoid those treated with creosote near food crops. Corrugated steel is increasingly popular — durable, long-lasting, and creates warmer growing conditions. Avoid treated pine (CCA) for food gardens — the copper arsenate treatment leaches into soil.

Dimensions

The standard recommendation is 1.2m wide (reachable from both sides without stepping in) and any length. Minimum depth for most vegetables is 30cm; 40–45cm is better for root crops. Line the base with permeable weed cloth to prevent grass growing up through the bed.

Filling

Fill with a quality mix: 50% quality topsoil or garden mix, 30% compost, 20% aged manure or additional compost. This is expensive to fill initially but amortises over many years of high-productivity growing. Top up with compost each season as the mix settles and organic matter decomposes.