Hardware cloth may be used to exclude chipmunks from flower beds. Seeds and bulbs can be covered by 1/4-inch (0.6-cm) hardware cloth, and the cloth itself should be covered with soil. The cloth should extend at least 1 foot (30 cm) past each margin of the planting. Exclusion is less expensive in the long run than trapping where high populations of chipmunks exist.
Resources: (online)
Chipmunks
