According to the USDA Hardiness Zone Chart, Houston lies mostly in zone 9a. The 'mostly' part comes in regarding our part of town where the temperatures can fall into the 20's often enough to consider us an 8b. The Texas Gardener's Chart at the Texas A&M Extension Service puts the entire Houston area in their zone 3 (which equates to zone 8 on the USDA chart).

With tender young plants, it is best to err on the side of caution regarding the temperatures they can withstand. If you are dealing with established 'woody' plants, there may be above-ground damage but the roots may still be healthy.

Our frost dates are pretty easy to remember. Based on a 50 year average, our first frost is just after December 7th (Pearl Harbor Day) and our last frost is just before February 14th (Valentine's Day). Just remember that these dates are based on averages and we can have earlier or later frosts. In 2002, our last freeze came in early April.