One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant primroses in Detroit can be determined by checking out the USDA zone info.

Planting Calendar for Primroses

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

Primroses are very cold tolerant which tells us that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant primroses in Detroit 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. If you wait any later than that and your primroses may not have a chance to grow to maturity. You can get started a little bit earlier by starting your primroses indoors.

Last Frost Date

In Detroit the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -5°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Detroit and it changes from year to year. Half of the time in Detroit there is a last frost after April 15 so just be sure to be ready to protect your primroses in the event of a surprise late frost.

USDA Zone Info for Detroit

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Detroit

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