4-4 Use Standard 15 Inch Chimney Block to hold slope Published May 4, 2011 at 800 × 600 in Gardening Made Easy – For Moderate to Arid Climates ← Previous / Next → Use Standard 15 Inch Chimney Block Chimney block is not only great material for creating unique and beautiful tiers in your garden, it’s makes for perfect planters for your spice garden. Versatile is good.