Retaining Wall Drainage: Weep Holes vs. Pipe Systems for Hillside Planters

In Southern California, winter rains—not summer irrigation—cause wall failures. If only the planter area drains to the wall, weep holes plus crushed stone behind them may suffice. If uphill runoff reaches the wall, install a gravel drain or perforated pipe to intercept water before it builds pressure. The extra $2,500 is insurance against catastrophic wall failure; many contractors require it for liability.