One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can determine when it's a good idea to plant polygonums in Watertown by checking out the USDA zone info.

Planting Calendar for Polygonums

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

It's a bad idea to plant polygonums until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant polygonums in Watertown 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. If you are starting your polygonums indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Watertown the average date of last frost happens on May 15. In the coldest months of winter you can expect an average low temperature of -25°F.

Keep in mind that USDA zone info for Watertown is just an average and the actual date of last frost changes from year to year. Since half of the time in Watertown there is a last frost after May 15 be ready to protect your polygonums in the event of one of those late frosts.

USDA Zone Info for Watertown

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 Watertown

You may be interested in your other planting guides for Watertown.