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

You can estimate when it's a good idea to plant polygonums in Sammamish by reviewing the USDA zone info.

Planting Calendar for Polygonums

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

Since polygonums do not do well in cold weather it's important to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant polygonums in Sammamish 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 grow to maturity. You can get started a couple of weeks earlier by starting your polygonums indoors.

Last Frost Date

The average date of last frost is March 15 in Sammamish. In the coldest months of winter you should expect an average low temperature of 15°F.

Since the USDA zone info for Sammamish is just an average the actual date of last frost will vary from year to year. Since half of the time in Sammamish it frosts late in the year after March 15 be ready to protect your polygonums in the event of one of those late frosts.

USDA Zone Info for Sammamish

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Sammamish

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