One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

The first opportunity to plant sweet potatos in Zone 4b should be determined by using the USDA zone info.

Planting Calendar for Sweet Potatos

Frost tolerance for sweet potatos:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since sweet potatos do not do well in cold weather you really should wait until after the last frost before you can plant them.

The earliest that you can plant sweet potatos in Zone 4b is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant sweet potatos and expect a good harvest is probably August. If you wait any later than that and your sweet potatos may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your sweet potatos indoors.

Last Frost Date

The average date of last frost is May 15 in Zone 4b. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Zone 4b is just an average the actual date of last frost is different every year. Since half of the time in Zone 4b you get a frost after May 15 be ready to cover your sweet potatos if you have a surprise late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.