Plant Heat Zones for Dallas-Ft Worth
The zones give the average number of days a year that an area has over 86 degrees temperatures. The temperature many plants apparently become affected by heat.
AHS Plant Heat Zone Map; http://www.ahs.org/gardening-resources/gardening-maps/heat-zone-map. You need to purchase the map, but Dallas, Ft Worth, north, west,& south is zone 9 (120-150 days). Rockwall, north & east is zone 8 (90-120 days).
Plant Maps Interactive Heat Zones Map for Texas; http://www.plantmaps.com/interactive-texas-heat-zones-map.php. Dallas Ft Worth is also in zones 8 (91 - 120 days > 86°F ) & zone 9 (121 - 150 days > 86°F), the zones area more intermingled through the area than the AHS map. Maybe based on older data from NOAA that doesn’t take the resent warming into consideration. Still, Plant Maps has maps for all over the world with some interactive maps that show street level results.
Sunset Climate Zones;
This is the most comprehensive of the zone maps. It takes the total climate into consideration; the length of the growing
season, timing and amount of rainfall, winter lows, summer highs, wind,
humidity, latitude, & elevation. They say “USDA Cold Hardiness zones show
where plants can survive the winter. Sunset’s zones show where plants will
thrive year round”. It is not always shown with plant information unless you
look up plants in Sunset’s books, but I see it mentioned on more websites. Not
all plants growing in this zone will grow here, mostly due to our black clay
soil, but those are the plants that may be more likely to do well here.
We are in ZONE 33. North-Central Texas and Oklahoma Eastward to the Appalachian Foothills:
Growing season: mid-April through Oct. Warm Gulf Coast air and colder continental/arctic fronts both play a role; their unpredictable interplay results in a wide range in annual rainfall (22" to 52") and winter lows (20 degrees to 0 degrees F/-7 degrees to -18 degrees C). Summers are muggy and warm to hot.