Drainage Behind a Low Hillside Planter Wall: Gravel, Pipe, and Footing Details

Gravel backfill: 4-6 inch layer behind wall
Perforated drain pipe: At base of gravel, daylighted or to soakaway
Volume calc: Length x Height x 0.5 ft = cubic feet ÷ 27 = cubic yards

Building a 12-18 inch cinder block planter wall on a 50-foot slope requires proper drainage, footing, and block selection.

Drainage System (Both Required)

Cinder blocks don't interlock well. Use segmental retaining wall units:

Even "cosmetic" walls retain soil. Undersized footings and wrong blocks fail within years.

Proper materials + footing = 50+ year wall. Shortcuts = 5-year failure. The cost difference is small; the longevity difference is massive.

Landscaping and Design: Retaining Wall with Drainage: Consult Local Expert; Garage Flooding: French Drain with Polyethylene Pipe and Gravel; Retaining Wall Failure: Contractor Responsibility and Documentation; Fixing Drainage Behind a Retaining Wall; Solving Backyard Drainage with French Drains and Check Dams; Evaluating a Segmental Retaining Wall: Batter, Alignment, and Drainage; Retaining Wall Drainage: When Weep Holes Aren't Worth the Cost; Stabilizing Driveway Edges on a Steep Hill: Crushed Aggregate Solution; Retaining Wall Drainage: Weep Holes vs. Pipe Systems for Hillside Planters; Building a Dry Well for Downspout Drainage

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