The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Houston you can estimate when it's possible to plant dahlias by reviewing the USDA zone info.

Planting Calendar for Dahlias

Frost tolerance for dahlias:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You really shouldn't plant dahlias until after the last frost because they do not do well in cold weather.

The earliest that you can plant dahlias in Houston is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant dahlias and expect a good harvest is probably September. If you wait any later than that and your dahlias may not have a chance to fully mature. You can get started a little bit earlier by starting your dahlias indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Houston. You can expect an average low temperature of 20°F in the coldest months of winter.

Remember that USDA zone info for Houston may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Houston you get a frost after February 15 be ready to cover your dahlias if you have a late frost.

USDA Zone Info for Houston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Houston

You may be interested in your other planting guides for Houston.