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

A common way of making a decision about when to plant primula is to use the USDA zone info for Columbia Falls.

Planting Calendar for Primula

Frost tolerance for primula:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Primula do well in pretty solid cold which means that you can plant them a lot earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant primula in Columbia Falls is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant primula and expect a good harvest is probably September. Any later than that and your primula may not have a chance to really do well. Starting your primula indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Columbia Falls. You can expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Columbia Falls is not always accurate the actual date of last frost changes from year to year. Half of the time in Columbia Falls it frosts late in the year after April 15 so make sure that you are ready to cover your primula if you have a surprise late frost.

USDA Zone Info for Columbia Falls

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 Columbia Falls

You may be interested in your other planting guides for Columbia Falls.