Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Zone 4b you can determine when you can plant polygonums by referring to the USDA zone info.

Planting Calendar for Polygonums

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

Since polygonums are not cold tolerant you have to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant polygonums 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 polygonums and expect a good harvest is probably August. Any later than that and your polygonums may not have a chance to fully mature. You can get started a little bit earlier by starting your polygonums indoors.

Last Frost Date

On average the last frost is on May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Always keep in mind that USDA zone info for Zone 4b is an average and the actual date of last frost changes from year to year. Half of the time in Zone 4b last frost occurs after May 15 so be sure to be ready to protect your polygonums if you have a 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.