Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By reviewing the USDA zone info for Harlan it's possible to figure out when 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.

Since polygonums are not cold tolerant you really should wait until after the last frost has passed before you can plant them.

The earliest that you can plant polygonums in Harlan 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. If you are starting your polygonums indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Harlan the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -20°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Harlan and it can change quite a bit from year to year. Since half of the time in Harlan there is a last frost after April 15 be ready to protect your polygonums in the event of a late frost.

USDA Zone Info for Harlan

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Harlan

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