The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The best time to plant polygonums in Watertown can be determined by using 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 not a good idea to plant polygonums until after the last frost because they are not cold tolerant.

The earliest that you can plant polygonums in Watertown 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. Any later than that and your polygonums may not have a chance to really do well. Starting your polygonums indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Watertown the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -20°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Watertown and it will vary from year to year. Half of the time in Watertown last frost occurs after April 15 so always be ready to cover your polygonums in the event of a surprise late frost.

USDA Zone Info for Watertown

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Watertown

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