The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of determining when it's the best time to plant primula is to consult the USDA zone info for Bozeman.

Planting Calendar for Primula

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

Primula do ok in cold weather which tells us that you can plant them earlier in the year than more sensitive plants.

The earliest that you can plant primula in Bozeman 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 primula and expect a good harvest is probably August. 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

The average date of last frost is May 15 in Bozeman. In the coldest months of winter you can expect an average low temperature of -25°F.

Keep in mind that USDA zone info for Bozeman is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Bozeman you get surprised by a frost after May 15 so make sure that you are prepared to protect your primula in the event of one of those late frosts.

USDA Zone Info for Bozeman

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 Bozeman

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