One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to estimate when to plant polygonums by checking out the USDA zone info for Kirkland.

Planting Calendar for Polygonums

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

It's a bad idea to plant polygonums until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant polygonums in Kirkland 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. You probably don't want to wait any later than that or else your polygonums may not have a chance to grow to maturity. Starting your polygonums indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on March 15 in Kirkland. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Kirkland is an average the actual date of last frost is different every year. Half of the time in Kirkland you get a frost after March 15 so just be sure to be ready to cover your polygonums if you have a surprise late frost.

USDA Zone Info for Kirkland

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 Kirkland

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