One of the first steps you take when you are getting a good idea your gardening schedule is find your 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.

It's possible to determine when you can plant zinnia by looking at the USDA zone info for Miles City.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You can not plant zinnia until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant zinnia in Miles City 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 zinnia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your zinnia may not have a chance to fully mature. Starting your zinnia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Miles City the average date of last frost happens on May 15. You can expect an average low temperature of -30°F in the coldest months of winter.

Remember that the actual date of last frost is an average because it is based on the USDA zone info for Miles City and it will vary from year to year. Half of the time in Miles City it frosts late in the year after May 15 so be sure to be ready to cover your zinnia in the event of one of those late frosts.

USDA Zone Info for Miles City

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 Miles City

You may be interested in your other planting guides for Miles City.