Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Kelso you can determine when it's a good idea to plant polygonums by looking at 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.

You should not plant polygonums until after the last frost because they are not cold tolerant.

The earliest that you can plant polygonums in Kelso 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 Kelso the average date of last frost happens on March 15. You should expect an average low temperature of 15°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Kelso and it can change quite a bit from year to year. Half of the time in Kelso you get surprised by a frost after March 15 so always be ready to protect your polygonums in the event of a surprise late frost.

USDA Zone Info for Kelso

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 Kelso

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