Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Petersburg you can determine when it's a good idea to plant helianthemum by referring to the USDA zone info.

Planting Calendar for Helianthemum

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

You can plant helianthemum a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant helianthemum 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 helianthemum and expect a good harvest is probably September. If you wait any later than that and your helianthemum may not have a chance to really do well. Starting your helianthemum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Petersburg. In the coldest months of winter you can expect an average low temperature of 5°F.

Just be sure to remember that USDA zone info for Petersburg is just an average and the actual date of last frost will vary from year to year. Since half of the time in Petersburg you get surprised by a frost after April 15 be ready to protect your helianthemum in the event of a 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.