Identifying Your USDA Hardiness Zone: Chino Hills, California

A resident of Chino Hills, California, was confused by conflicting zone information: some sources said USDA Zone 10, while Sunset Western Gardening books placed the area in Zone 18.

Clarification

Tom explained that the area is more accurately USDA Zone 9b, not Zone 10, which is typically reserved for coastal Southern California. Chino Hills is inland near Pomona and Whittier, making 9b a better fit. The Sunset Zone 18 designation aligns with this assessment. Tom noted he is more familiar with USDA maps than the Sunset system.

Knowing your correct hardiness zone ensures appropriate plant selection for long-term garden success.