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.

The USDA zone info for Washington should be reviewed to estimate when it's a good idea to plant polygonums.

Planting Calendar for Polygonums

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

Polygonums are not cold tolerant which means that it is important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant polygonums in Washington 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 little bit earlier.

Last Frost Date

In Washington the average date of last frost happens on April 15. It might get as low as -10°F during the coldest months of winter.

Remember that USDA zone info for Washington is just an average and the actual date of last frost is different every year. Half of the time in Washington you get a frost after April 15 so just be sure to be ready to protect your polygonums in the event of a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Washington

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