One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to estimate when it's a good idea to plant calendula by reviewing the USDA zone info for Tulsa.

Planting Calendar for Calendula

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

You can plant calendula just a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant calendula in Tulsa 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 calendula and expect a good harvest is probably September. If you wait any later than that and your calendula may not have a chance to fully mature. If you are starting your calendula indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Tulsa the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Since the USDA zone info for Tulsa is just an average the actual date of last frost changes from year to year. Since half of the time in Tulsa there is a last frost after April 15 be ready to cover your calendula if you have a late frost.

USDA Zone Info for Tulsa

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Tulsa

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