The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of determining when you can plant polygonums is to look at the USDA zone info for Winthrop Harbor.

Planting Calendar for Polygonums

Frost tolerance for polygonums:	Not tolerant of frost.
When to plant:	After the last frost.

Polygonums do not do well in cold weather which means that you need to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant polygonums in Winthrop Harbor is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant polygonums and expect a good harvest is probably August. You probably don't want to wait any later than that or else your polygonums may not have a chance to really do well. You can get started a little bit earlier by starting your polygonums indoors.

Last Frost Date

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

Since the USDA zone info for Winthrop Harbor may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Winthrop Harbor you get surprised by a frost after April 15 so always be ready to protect your polygonums if you have a surprise late frost.

USDA Zone Info for Winthrop Harbor

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Winthrop Harbor

You may be interested in your other planting guides for Winthrop Harbor.