Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 Havre you should be able to determine when it's the best time to plant mustard.

Planting Calendar for Mustard

Frost tolerance for mustard:	Not tolerant of frost.
When to plant:	After the last frost.

Mustard are not cold tolerant which tells us that you have to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant mustard in Havre is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant mustard and expect a good harvest is probably August. If you wait any later than that and your mustard may not have a chance to grow to maturity. Starting your mustard indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Havre. You can expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Havre is not always accurate the actual date of last frost changes from year to year. Half of the time in Havre there is a last frost after May 15 so make sure that you are prepared to protect your mustard in the event of one of those late frosts.

USDA Zone Info for Havre

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Havre

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