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 reviewing the USDA zone info for Zone 4b you should be able to determine when you can plant missouri primrose.

Planting Calendar for Missouri Primrose

Frost tolerance for missouri primrose:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Missouri Primrose do well in mild cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant missouri primrose in Zone 4b is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant missouri primrose and expect a good harvest is probably August. If you wait any later than that and your missouri primrose may not have a chance to grow to maturity. If you are starting your missouri primrose indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Zone 4b is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 4b you get surprised by a frost after May 15 so always be ready to cover your missouri primrose if you have one of those late frosts.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.