The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to determine when it's possible to plant calendula by using the USDA zone info for Houston.

Planting Calendar for Calendula

Frost tolerance for calendula:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Calendula are moderately cold tolerant which tells us that you can start planting them earlier than more sensitive plants.

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

The last month that you can plant calendula and expect a good harvest is probably October. You probably don't want to wait any later than that or else your calendula may not have a chance to grow to maturity. Starting your calendula indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Houston the average date of last frost happens on February 15. It might get as low as 20°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Houston and it is different every year. Since half of the time in Houston you get surprised by a frost after February 15 be ready to cover your calendula in the event of 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.