One of the best tools that you have as gardeners to help us determine 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.

By using the USDA zone info for Spearfish it's possible to estimate when it's the best time to plant primroses.

Planting Calendar for Primroses

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

Primroses do well in pretty solid cold which tells us that you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

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

Last Frost Date

On average all chance of frost has passed is on April 15 in Spearfish. It might get as low as -20°F during the coldest months of winter.

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

USDA Zone Info for Spearfish

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 Spearfish

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