Concrete (cinder) blocks

Concrete blocks are an affordable, durable raised bed material that can last virtually forever. Modern concrete blocks (often called cinder blocks) are safe for food gardens; they have not contained fly ash since the 1970s. University extension services widely recommend them. At $2-3 per block, a single-layer 4x8-foot bed costs approximately $30-50. The hollow cores face up and can be filled with soil to grow herbs, strawberries, or flowers as bonus planting space. Stack blocks in a running bond pattern (offset joints like a brick wall) for stability. For beds taller than one layer, drive rebar through corner block holes into the ground for reinforcement. Caveats: blocks may slightly raise soil pH over time due to calcium leaching, which can be managed with sulfur amendments if growing acid-loving plants. They retain heat similar to metal beds. Blocks weigh about 35 lbs each, so enlist help for multi-layer builds. For extra peace of mind about leaching, line interior walls with 6-mil poly sheeting. You can sit on the blocks while gardening, which is a genuine ergonomic benefit.