The USDA Zone info is a great tool for gardeners to help us estimate 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.

By looking at the USDA zone info for Ketchikan it's possible 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 the last frost when the weather gets warmer.

Since polygonums require warm weather you really should wait until after the last frost has passed before you can plant them.

The earliest that you can plant polygonums in Ketchikan 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. If you wait any later than that and your polygonums may not have a chance to fully mature. You can get started a little bit earlier by starting your polygonums indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Ketchikan. It might get as low as 5°F during the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Ketchikan and it is different every year. Half of the time in Ketchikan last frost occurs after April 15 so be sure to be ready to cover your polygonums in the event of one of those late frosts.

USDA Zone Info for Ketchikan

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Ketchikan

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