One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Houston can be read to estimate when to plant petunias.

Planting Calendar for Petunias

Frost tolerance for petunias:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since petunias are barely cold tolerant you can plant them slightly earlier in the year than other plants that might not handle the cold.

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

The last month that you can plant petunias and expect a good harvest is probably September. If you wait any later than that and your petunias may not have a chance to really do well. Starting your petunias indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on February 15 in Houston. It might get as low as 20°F during the coldest months of winter.

Since the USDA zone info for Houston may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Houston you get a frost after February 15 so make sure that you are ready to protect your petunias if you have a surprise 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.