One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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.

A way of making a decision about when you can plant primula is to use the USDA zone info for Spirit Lake.

Planting Calendar for Primula

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

Primula are one of those plants that can tolerate quite a bit of cold weather which means that you can start planting them much earlier than more sensitive plants.

The earliest that you can plant primula in Spirit Lake 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. If you wait any later than that and your primula may not have a chance to grow to maturity. If you are starting your primula indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Spirit Lake 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.

Since the USDA zone info for Spirit Lake is just an average the actual date of last frost will vary from year to year. Half of the time in Spirit Lake 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 Spirit Lake

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 Spirit Lake

You may be interested in your other planting guides for Spirit Lake.