One of the first steps you take when you are estimating your gardening schedule is find your 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.

In Kalispell you can determine when it's a good idea to plant polygonums by referring to the USDA zone info.

Planting Calendar for Polygonums

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

You really shouldn't plant polygonums until after the last frost has passed because they require warm weather.

The earliest that you can plant polygonums in Kalispell 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 few weeks earlier by starting your polygonums indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Kalispell. You should expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Kalispell is just an average the actual date of last frost is different every year. Half of the time in Kalispell there is a last frost after April 15 so make sure that you are prepared to cover your polygonums in the event of one of those late frosts.

USDA Zone Info for Kalispell

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 Kalispell

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