One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The best time to plant calendula in Petersburg should be figured out by referring to the USDA zone info.

Planting Calendar for Calendula

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

Since calendula are one of those plants that can tolerate a little bit of cold weather you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant calendula in Petersburg 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 really do well. Starting your calendula indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Petersburg. It might get as low as 5°F during the coldest months of winter.

Always keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Petersburg and it changes from year to year. Half of the time in Petersburg you get surprised by a frost after April 15 so make sure that you are prepared to cover your calendula if you have a surprise late frost.

USDA Zone Info for Petersburg

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Petersburg

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