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.

The first chance to plant bunching onions in Petersburg should be determined by reviewing the USDA zone info.

Planting Calendar for Bunching Onions

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

Since bunching onions are one of those plants that can tolerate a tiny bit of cold weather you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant bunching onions in Petersburg is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant bunching onions and expect a good harvest is probably August. Any later than that and your bunching onions may not have a chance to grow to maturity. If you are starting your bunching onions indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Since the USDA zone info for Petersburg is just an average the actual date of last frost changes from year to year. Since half of the time in Petersburg you get surprised by a frost after April 15 be ready to cover your bunching onions 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.