The U.S. Department of Agriculture Plant Hardiness Zone Map separates the Americas into 11 zones based on annual average low temperatures. Each zone is numbered and represents a spread of 10 degrees. The zones are divided into sub-zones, each of which represents five degrees. On many seed packets and potted plants are included advisories that indicate to customers which of the zones are best suited for the products. According to such recommendations, white sage is hardy in zones 7 through 10.
Zone 7 passes through the southern states from North Carolina down through north Texas and a few small areas throughout the western United States. Sub-zone 7a temperatures fall as low as zero while sub-zone 7b temperatures drop as low as 5 degrees. When growing white sage in zone 7, bring the plants inside during winter and any other cold weather.
Zone 8 spans the lower southern states from South Carolina and along the southern border. It loops up through Arizona, Nevada and eastern California. Zone 8 includes the coast of Oregon and Washington. Sub-zone 8a temperatures drop as low as 10 degrees. Bring white sage grown in sub-zone 8a indoors during winter. Sub-zone 8b temperatures fall as low as 20 degrees, which is the lowest temperature white sage can tolerate.
White sage grows wild in zone 9's desert regions of southern California. Other areas in which white sage is hardy are central Florida, southern Texas and along the California coast. Sub-zone 9a gets as cold as 20 degrees while sub-zone 9b's average low temperature ranges from 25 to 30 degrees. White sage grows well throughout zone 9.
White sage flourishes in zone 10, which includes very little of the United States. The zone stretches across the southernmost areas of Florida and California and across Mexico, where white sage grows wild in abundance. The average annual low temperature in sub-zone 10a ranges from 30 to 35 degrees. In sub-zone 10b, the range is 35 to 40 degrees. Although the lowest temperatures in zone 10 each year pose no threat to white sage, the plant cannot tolerate that zone's hottest temperatures, which sometimes exceed 110 degrees.