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

The best time to plant asters in Havre can be estimated by reviewing the USDA zone info.

Planting Calendar for Asters

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

Since asters are one of those plants that can tolerate a little bit of cold weather you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant asters in Havre 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 asters and expect a good harvest is probably August. Any later than that and your asters may not have a chance to really do well. If you are starting your asters indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

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

Remember that USDA zone info for Havre 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 Havre you get surprised by a frost after May 15 so be sure to be ready to cover your asters in the event of a surprise late frost.

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.